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AQUARIA FAQ: Plants

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Nov 13, 1996, 3:00:00 AM11/13/96

Archive-name: aquaria/general-faq/plants
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This FAQ available on the WWW via http://www.cco.caltech.edu/~aquaria/Faq/

FAQ: Aquatic Plants

In this FAQ you will find information on all aspects of freshwater
live plantkeeping (also known as Aquatic Gardening). We also include
detailed information on lighting, algae and snails which may be useful
to _all_ aquarists.

Copyright

The FAQs owe their existence to the contributors of the net, and as
such it belongs to the readers of rec.aquaria and alt.aquaria.
Articles with attributions are copyrighted by their original authors.
Copies of the FAQs can be made freely, as long as it is distributed at
no charge, and the disclaimers and the copyright notice are included.

Contents

Basics Q&A
Lots of basic questions answered spanning the whole range of
topics from appropriate fish to heating cables.

Plant Survival
A shorter and more narrative introduction to plant keeping.

Plant Listing
A descriptive list of most common aquatic plants, including a
``blacklist'' of false aquatic plants.

Lighting
Duration, intensity, and how to make your fluorescent fixture
turn on by itself.

CO2
The compressed bottle method.

Substrate Heating
Why do it, construction hints.

Resources
Mail-order sources, books, magazines, an e-mailing list for
aquatic gardeners, more detailed articles, etc.

FAQ: Aquatic Plant Q&A

Contributed by Erik Olson

Answers to your questions are available on the following plant topics:
* General Questions
* Fish
* Lighting
* Carbon Dioxide (CO2)
* Nutrients and Fertilizer
* The Substrate
* Heating
* Long Term Success

General Questions

``What do you absolutely need to grow plants?''

Successful plant growth requires a balance of light, nutrients, trace
elements, and carbon dioxide (CO2). The light should be provided in a
spectrum the plants can absorb, must be of great enough intensity to
keep the plant alive, and should be consistently on 10-14 hours a day.
Most nutrients are supplied by fish waste. Trace elements _may_ also
be supplied in your tap water, but can be supplied by commercial trace
element mixtures. CO2 is supplied partly from the air and partly by
your fish, but can be enhanced by injecting it from an external source
(for example, a compressed bottle). If your plants have a deficiency
of even one of these factors, their growth will be limited. (Don't
panic about this; most of us don't need optimal plant growth.) Each
will be discussed in detail in the following sections.

``My friend grows plants beautiful plants and doesn't do stuff like CO2 or
fertilizers. Is it really necessary?''

The quick answer to this is _no_. It is completely possible to grow
plants using basic tank equipment, either by chance or by patiently
learning through trial-and-error. This is accomplished by slight
modification of the basic equipment and usual fishkeeping practice.
High-tech gadgetry, however, can remove much of the guesswork by
allowing you to better control each of the four success factors.

We should also mention that the term _beautiful_ is a bit subjective
here; Some hobbyists achieve great success with ``easy'' plants and no
special equipment, and this is perfectly fine. But beware comparing
this to a high-tech monger and their ability to grow a wider variety
of plants, because they're really two different categories!.

``How do I disinfect my plants?''

* A ten minute soak in potassium permangenate (pale purple) works
well; it is available in dilute form from Jungle products as
"Clear Water". Permangenate is particularly good for killing
bacteria and pathogens.
* A 2-day soak in 1 tbsp/gallon of alum (buy it at drug stores) is
good for killing snails and their eggs.
* If the plants are kept in a fish-free system for three weeks,
parasites like ich and velvet will die without their fish hosts.
* Soak plants in a 1:19 diluted bleach solution; 2 minutes for stem
plants, 3 minutes for tougher plants. Make sure to remove all
traces of bleach afterwards by rinsing with water and
dechlorinator. This method can kill your plants, so use only as a
_last resort_ against hell algae.

(See the ALGAE SECTION of the DISEASE FAQ for more algae-prevention
tips, and the SNAIL SECTION of that same FAQ for snail prophylaxis.)

``Do I leave my new plants in the pot?''

Many aquatic plants are now sold in potted rockwool. Plants with
delicate roots, such as _Cryptocoryne_ and _Anubias_, are usually best
left in the rockwool wadding, especially if you have to move them
around in the tank. Leaving them potted also can reduce transplant
shock; otherwise you must be patient and allow the plants time to
recover in their new substrate. You can bury the pots in your gravel
to conceal them. Some folks like to cut away the plastic pot, and just
leave the plant in the wadding so it can grow out into the substrate.

Fish

``What kind of plants can I keep with fish X?''
``What kind of fish can I keep with plant X?''

These are essentially the same question, though asking the second one
shows you are a serious plant person. You need to match the habits of
the fish with the plant. Big cichlids that like to dig should not be
kept in a tank with rooted plants, though floating (or ephiphytic)
plants are fine. Vegetarian fish should not be kept in a tank with
plants they like to eat, unless the plants grow faster than they
destroy them! Some algae-eating fish also turn out to be plant-eaters
too. In general, try and learn the habits of your fish before you buy
them and your plants, and be prepared to find out what works by
several trials.

Some fish that can be kept with virtually any plants: small tetras,
danios, rasboras, gouramis, discus, bettas, angelfish (Pterophylum),
rainbowfish, Corydorus catfish, livebearers, killifish, dwarf
cichlids, and in general most small fish.

Lighting

``How much light do I need''

The ``classic'' rule of thumb for lighting is 2-4 watts per gallon
(0.5-1 watts/l) for a tank of normal depth, less than 24 inches
(60cm). The actual requirements also depend on depth, so you could get
away with 1-2 watts per gallon with a 12 inch deep tank, but would
need more than 4 watts for a tank deeper than 24 inches. For plants
that demand medium to high light, most people find they need at least
two fluorescent fixtures of the length of normal tanks (20-gallon
(80l), two 24 inch tubes; 55-gallon (200l), two 48 inch tubes). More
detailed calculations can be found in the later LIGHTING section.

``Can I grow plants with my single strip light?''

Yes, you can, though you are limited to the lowest-light plants and
will get very slow growth. Some of these include Java fern, Anubias,
Cryptocoryne species, water sprite and Java moss. Some of these
plants, notably _Cryptocorynes_, actually _prefer_ lower light. We
should also mention that some people may have luck with plants that
normally prefer higher light, but the odds are that they will grow
slowly and stunted.

``What kind of bulb do I need?''

First and foremost, don't use incandescent lights; they generate far
too much heat and not enough light. Full-spectrum fluorescent bulbs
are ideal, since they duplicate the spectrum of the sun. These tubes
(``Vitalite'', ``Spectralite'') cost between $8 and $20. Cheaper
``plant lights'' are also good, and may actually bring out your fish's
color better. Tri-phosphor bulbs (Triton, Tri-lux) are slightly more
powerful, but also more expensive than full-spectrum bulbs, and
high-end bulbs with internal reflectors (BioLume) are overpriced and
unnecessary. Other bulbs to avoid are standard cool-white tubes, and
``aquarilux'' tubes, designed to show off the fish and retard plant
growth, though some folks have had success with a mixture of cool
white and plant bulbs.

``What's MH? Is it better than fluorescent?''

Metal Halide (MH) lights are most commonly seen illuminating football
fields, but are also used in our hobby by reefkeepers and die-hard
plant enthusiasts, who demand very high light intensity. The fixtures
cost significantly more than fluorescent (over $200 per fixture). The
bulbs last longer and provide more efficient and brighter illumination
than fluorescents (typically 175-250 watts per bulb), but generate an
appropriately higher level of heat as well. Some aquarists like the
sun-like shadow effects generated by MH bulbs.

Do not confuse MH with the tungsten halogen lights sold in hardware
stores as utility floods or living room fixtures; Halogen lights are
basically high-wattage incandescent lights, and generate an enormous
amount of heat and are very inefficient in their light output.

``How do I add another light to my tank?''

If you can fit a second tube in your existing hood, many stores sell
upgrade kits to add the second fixture. Otherwise, you might be able
to add a second hood to the tank, or you can find a replacement
two-bulb hood (mail-order places sell them). Another option for 4-foot
(130cm) long tanks is to buy a ``shoplight'' fixture and lay it across
the top over the glass. You can also build your own hood or canopy and
mount the shoplight or fixture inside. It's possible to omit the
fixture by purchasing special end caps and clips for the tubes. These
are available, with ballasts, from aquarium stores and are commonly
used by marine aquarists.

``How long do I leave the light on each day?''

Plants want a definite daily light and dark cycle each day; 10-14
hours is fine; twelve hours is the duration on the equator, where many
tropical plants are found. You should buy a timer ($5-10) to
automatically turn the lights on and off for you, since the plants
(and fish) prefer a regular cycle to an erratic one. If the plants
need more light, you should _not_ extend the light period, as that
will only help the algae. Rather, install another fixture and increase
the _intensity_ of light.

Speaking of timers, many fluorescent fixtures don't self-start, i.e.
you have to hold in a button for a few seconds to turn it on. You can
quickly convert any fixture into a ``self-starting'' one with a few
new components from a hardware store or sold as a kit from mail-order
houses. See the later LIGHTING section for a diagram.

``How often do I change the bulb?''

Most fluorescent bulbs lose a major portion of their intensity after
six months, so they should be replaced every 6-12 months. If that
seems expensive to you and you can live with the reduced light level,
you can cheat and wait until the bulbs burn out after two years (that
is, according to TAG editor Neil Frank, what ``many experienced plant
enthusiasts'' do). It is best to stagger the replacement on multi-bulb
tanks in order to avoid dramatic intensity changes.

``Won't increased light fill my tank with algae?''

If you are adding that second light to your tank for the first time,
you should be prepared for this. Increased light is welcomed by both
algae and plants, so the plants must out-compete the algae. You can
help tip the balance in the plants' favor by maintaining a low fish
population, keeping algae eaters, and frequent water changes (see the
ALGAE SECTION of the DISEASE FAQ).

Carbon Dioxide (CO2)

``Is CO2 injection really necessary?''

CO2 injection is not required to grow plants. However, most people
with CO2 feel that, aside from high-intensity lighting, CO2 is the
most important step to getting _excellent_ growth. In fact, as light
intensity is increased, plants will require more nutrients, including
carbon which is derived from CO2. In conjunction with carbonate
buffers (see the WATER CHEMISTRY section of the BEGINNER FAQ), CO2
injection will buffer your water to a neutral or low pH. Lower pH will
help plants get access to certain nutrients. Some also report CO2
injection keeps algae down.

``Isn't CO2 expensive?''

The startup cost can be a bit steep; expect to pay around $500 for a
fully-automated Dupla system, $350 for a manual injector. If you do it
yourself using welding or bar supplies, you can drop the price to
$100-$200 for a tank, regulator, and needle valve. After your initial
investment, CO2 refills (try fire extinguisher or beverage service
outlets) are cheap: $5-10 a year for a 5 lb cylinder.

If this is still too much, try the ultra-cheap _Yeast Method_ of
brewing CO2 (see below).

``How much CO2 is normal?''

The optimum dissolved CO2 level in an aquarium is 15-20 ppm. Some
references say that levels above 25ppm poison your fish, but general
experience is that this doesn't happen. The amount found in the water
from atmospheric concentrations varies by elevation and temperature,
but is less than 1ppm.

``How does the compressed gas method work?''

A compressed gas cylinder supplies CO2 at a high pressure of 800-1200
PSI. This is dropped to 5-20 PSI through a regulator, and reduced to a
few bubbles per second by a fine-control ``needle valve''. This slow
bubbling must be dissolved in your aquarium's water, through either a
gas reactor (which lets water and gas mix in a chamber much like a
trickle filter), an inverted jar (which just lets the gas diffuse into
the water slowly), or by injecting the bubbles into the intake of a
power or canister filter (the impeller ``chops'' them up into smaller
bubbles, many of which dissolve). The reactor is the most efficient
method, while the power filter injection is the easiest to try.

It is important to have control over the rate of injection, as too
much CO2 can kill your fish. Expensive ``automatic'' systems use an
electronic pH meter to regulate the amount of CO2 in the water by
shutting off the gas when the pH drops too low. ``Manual'' systems
require you to start with very low injection and gradually increase
over several days, all the time carefully monitoring pH drops and CO2
bubble rate in order to find the correct needle valve setting.

Construction and operational details can be found in the later CO2
SECTION.

``How does the yeast method work?''

CO2 is generated by fermentation of sugars in a bottle (just like when
brewing beer!) and then injected into the tank using the same methods
described above. The parts are _very_ cheap and easier to set up than
the compressed tank. The main drawback is that CO2 generation rate can
be erratic, and will quit on you if you do not change the solution
(once every two weeks or so) or get the mixture right. The CO2 level
generated is lower than that of compressed gas tanks, but is still
enough to help plant growth. Initially passed off as ``useless'' by
much of the aquarium literature, this technique has enjoyed a certain
vogue in the last year as a good way to try CO2 without draining your
wallet.

Here is one quick construction method: Tap the cap of a 2-liter
plastic soft drink bottle (the author uses drip-irrigation taps, which
can be obtained cheaply at local hardware stores) so that an airline
tube can feed the gas into your tank. Half fill the bottle with water,
and add 1/2 tsp yeast and 1/2 cup sugar. The solution will last about
two weeks, after which you can throw it out and start a new batch.
Beware of water siphoning back from your tank... put a check valve
in-line with the airline tube.

``Can I just dump carbonated water into my tank?''

No! Plants need a slow continuous source of CO2. If you dump
carbonated water in, it will spike the pH (stressing your fish), and
the CO2 will just dissipate back into the air within a few hours.

``Does injecting CO2 reduce the oxygen content?''

No. The level of dissolved CO2 and oxygen are actually _independent_
of each other; high levels of both can exist at the same time.
Furthermore, if you have a set of healthy plants, they will be
saturating the water with oxygen on their own. The problem is that
many of the techniques used to increase oxygen content (airstones,
trickle filters, keeping the water moving at the surface) also cause
CO2 to diffuse out of the aquarium; i.e., if you turn off your
airstone in order to keep the CO2 in, you might also reduce your
oxygen content. The best solution is to keep the water moving at the
surface of the tank, but inject CO2 faster than it can escape, giving
you high levels of both CO2 and oxygen.

Nutrients and Fertilizer

``Is fish food enough to fertilize my plants?''

Fish food usually provides enough of the three _macro_nutrients,
nitrogen, phosphate, and potassium (N-P-K), to keep your plants
healthy. However, the trace elements such as iron are not all supplied
in a form that the plants can use. Some trace elements may be in your
tap water, so frequent water changes will replenish them. This may
provide enough for some plant growth, but if you want the best growth
you should consider adding a trace element fertilizer.

``Can I use normal plant fertilizer?''

Normal land plant fertilizer contains high amounts of N-P-K which is
already supplied by the fish food. Adding more will cause algae
outbreaks and possible fish stress. You may be able to find a
trace-element-only fertilizer at better garden shops, or even mix your
own. Aquarium-specific mixes by Dupla (available world-wide) and
Dennerle (not available yet in the U.S.) are expensive, but are proven
to work very well. Beware some other brands that supply N-P-K (check
the label for ingredients; some do not list their contents for this
exact reason.) Fertilizer tabs, or even 1/4 inch pieces of ``plant
sticks'' (without sulfates) have been successfully used if placed
deeply in the substrate and used sparingly.

``How do I know if I need fertilizer?''

Lack of fertilizer shows up in your plants, as sickly transparent or
yellow leaves, as holes in the leaves, and as reduction in plant
growth. Old leaves die off more quickly than they are supposed to, and
the new leaves are small and stunted. Another symptom is the plants
grow very well for a month or so after you buy them, but then stop as
their internal supply of trace elements and macro nutrients run out.
You also need to add fertilizer if you have high levels of CO2 and
lighting, but no plant growth.

``How do I know which nutrient is limiting plant growth?''

This is always difficult to answer without actually _trying_ it
yourself. If you have slow growth and it picks up shortly after you
change your water, then your water is probably supplying some trace
elements which get depleted later; consider adding a trace element mix
or changing your water more often. If you have slow growth, but it
picks up after adding trace element mix, problem solved! If you have
slow growth but it picks up after feeding your fish a little bit more,
problem solved! But watch out that you don't increase things too
drastically, or you'll get algae blooms.

``How much is too much?''

If you like keeping zillions of test kits, then you can check some
trace element levels with them (Dupla recommends an iron level of
0.1ppm). Ammonia and nitrate test kits will tell you if you are
overfeeding. Alternatively, you need to watch your tank. Too much
fertilizer and fish food may show up as excessive algae growth.

The Substrate

``What should I put in my substrate?''

Gravel or sand is a good start! Size is an issue; with small grains
the roots might not be able to get a good hold and the sand tends to
compact, while larger gravel has a tendency to collect pockets of
rotting detritus. Most believe the ideal size is 2-3mm (#8) gravel,
while a few others like 1-2mm coarse sand (though it may be harder to
find). Malaysian trumpet snails (see the ALGAE SECTION of the DISEASE
FAQ) will burrow into the substrate and keep it aerated. The bottom
1/3 of the gravel can be supplemented with a fertilizer, of which
popular choices are peat (softens water), laterite (a clay containing
iron, usually used with undergravel heating systems), and soil. One
word of warning: if you use an undergravel filter, it may suck your
fertilizer back into the tank instead of keeping it with the bottom of
the gravel. Dupla makes special laterite balls which can be used in an
UGF (though expensive).

``How deep a substrate?''

In general, it's good to match the substrate with the types of plant
(or types of roots). For instance big Amazon Sword plants like deep
gravel of 4 inches (10cm), but _Lilaeopsis_ grass can do fine with an
inch or less. This can be helped by terracing the back of your tank to
be deeper and planting your deep-rooted plants there. You also can't
go wrong with a uniform 3 inches (7cm) of gravel all-around.

``Can you grow plants with an undergravel filter (UGF)?''

Oh my yes! Make sure you have enough gravel for the plants to be
happily rooted. It should also work best with a very slow flow rate.
Pluses of UGF may be an increased circulation to the roots. However,
you will probably get roots growing in the plates, it will be harder
to vacuum everything, and will be a major pain to pull and replant.
Many feel so strongly that you _shouldn't_ grow plants with an UGF
that it has become a bit of a religious issue on Usenet. However, this
does not mean it is not possible... like most religious issues, it is
something for which you must make your own decision. :)

Heating

``What temperature do I keep a planted tank?''

This varies from plant-to-plant, but you can keep most aquatic plants
from 72-80F (22-27C). For warm-water discus tanks, check a plant book
for species that thrive in these special conditions.

``Do I need to have substrate heating?''

The exact benefits of substrate heating have not been proven yet, but
it is believed they provide _long-term_ stability to a tank. If you
are a beginner, it's hardly worth messing with before mastering the
basics (fertilization, lighting, etc). If, though, you are a gadget
freak or love to spend money, you may get a sense of pride from
installing a cable heating system. (Some believe that a very slow UGF
can provide the same benefits.)

Long Term Problems

This list is by no means exhaustive! Please feel free to suggest more
long-term problems that can be addressed here.

``The leaves turned yellow and fell off.''

``The leaves got holes & fell off''

Might be a trace-element deficiency, or in the latter case, fish and
plants eating them.

``It grew for a while & then died/still grows, but slower.''

This is by far the most common problem beginners experience, and has
several different causes.
1. Plants can store some nutrients and trace elements, using them
later. When they come from the greenhouse, they are fully stocked.
But after a month or more, if you do not supply them with a
balance of nutrients they take what's missing from their stock.
When the stock's gone, the plant dies.
2. Most _potted_ plants are grown emersed (hydroponically) in
greenhouses, and are used to growing in very high light (i.e.
filtered sunlight) and with high levels of nutrients, and must
acclimate to aquarium conditions. First, they'll lose the old
leaves which were growing out of the water and produce new leaves
that have a different shape and firmness. Secondly, as they
acclimate to the lower light and nutrient levels their growth rate
will temporarily slow down.
While potted plants ship well, this may not be true for
_non-potted_ plants. They may have been stressed by passing
through many hands from grower or collector to wholesaler to
retailer, so they may not be in optimum condition when you acquire
them. The non-potted plants were most likely grown underwater, but
also outdoors under filtered sunlight, so they also must acclimate
to the aquarium conditions.
3. The plant might not be a true aquatic plant. Many stores pass off
land plants as aquatics (see our BLACKLIST). These plants can
manage to stay alive for a month or more, but eventually succumb.
4. Some plants go into hibernation. Aponogeton bulbs will lose all
their leaves, at which point they should be removed from the tank
and kept in cold water for a few months. Then they can be
replanted and will send out new leaves.
5. Cryptocorynes will ``melt'' all their leaves on a change in water
chemistry. Don't despair, eventually they will send out new
leaves.

``My ... grows great but everything else dies''

Some plants are hardier than others, and will grow in lower light,
CO2, or worse water conditions than others. However, some plants will
actually out-compete others for the available nutrients, and some
plants will not do well in the presence of other species; try moving
the other plants into a different tank if you can.

``My ... is covered with algae!''

Please read the ALGAE SECTION of the DISEASE FAQ for details on
specific algaes and remedies. But to summarize, you can keep
algae-eating fish to munch on it, starve it for nutrients by adding
floating or fast-growing plants that consume nutrients faster than the
algae, harvest some plants and remove dying leaves often to take
nutrients out of the tank, reduce feeding (or increase water changes
if you must overfeed), reduce the number of light hours per day, use
root fertilization instead of liquid leaf fertilization, or physically
remove it from the tank. There are also antibiotics for blue-green
algae and other algicides, but the latter can kill your plants as
well; use with caution!

FAQ: Plant Survival

contributed by George Booth

Plants need certain things to grow: light, CO2, nutrients and trace
elements. This should be no surprise. What is generally not known is
that plants need these things in fixed proportions (and unfortunately,
the proportions vary with each type of plant). For example, if you
have plenty of light, CO2, nutrients and most trace elements but not
enough of one specific trace element for a plant, the trace element in
short supply will determine how well that plant grows even though
other plants do fine. This explains why some plants are "easier" than
others - their needs are typically supplied by tap water or other
incidental sources. If the plants aren't able to utilize all the
nutrients due to a shortage of one or more specific elements, the
"excess" nutrients and light energy will be wasted or be used by
algae.

In general, there is no information available that says "this plant
needs this much light, CO2, nutrients and trace elements". Aquarists
can only determine "what works for me" by tedious trial and error.
Aquarists who follow the Dupla "Optimum Aquarium" regimen try to
ensure that all the requirements of all the plants are met, but this
leads to expensive and complex systems.

LIGHT

Light is very important for photosynthesis since it supplies the
energy required to drive the chemical reactions involved. The plants
use light energy primarily in the blue and red spectrum but an
aquarium will look better to people if full spectrum lighting is used.

Light intensity and spectrum are more important than duration. You
can't make up for dimmer bulbs by leaving them on longer. 10-12 hours
per day is usually sufficient. You need about 1.5 to 3 watts per
gallon, with deeper tanks requiring more intensity.

It is important to balance light intensity with other nutrients.
Intense lighting will be wasted if not enough CO2 and nutrients are
available to support the needs for photosynthesis.

CO2

This is very important to plant growth. Without sufficient quantities
of dissolved CO2, photosynthesis cannot take place. Most tanks will
have some CO2 due to fish respiration but this is usually not enough
to get "lush" growth. Some plants do not need much CO2 and some plants
like Cryptocorynes actually seem to do worse with higher levels of
CO2.

Typical levels of CO2 in a non-CO2-injected aquarium are in the range
of 1-3 ppm. Most plants will flourish with levels of 10-20 ppm but
this requires some type of CO2 injection. With lower levels of CO2,
the plants will not be able to utilize high levels of light and
nutrients and the extra light and nutrients will be used by algae.

NUTRIENTS

Beyond the "building blocks of life" provided by water and CO2
(oxygen, hydrogen and carbon), two other important nutrients are
required: nitrogen and potassium. Nitrogen is usually available in
sufficient quantities from fish waste in the form of ammonium (NH4+).
Most plants will prefer ammonium but some will use the end product of
the nitrification cycle, nitrate (NO3-). Ammonium is the preferred
source since it takes less energy to use that form of nitrogen. A good
test for ammonium levels is to monitor nitrates. If the nitrates are 0
ppm, you know that all the nitrogen is being used. This may indicate
that some plants are starving for nitrogen. It also might indicate
that a perfect balance has been achieved, but that is unlikely.

Potassium (K+) is also usually available from fish food.
Unfortunately, potassium is difficult to measure in the water. If
there are enough nitrates, there is usually enough potassium. Some
fertilizers contain additional potassium and can be used to be on the
safe side.

TRACE ELEMENTS

Trace elements are those things required in very small quantities yet
are still vital to plant growth. These are taken in by the plant in
ion form. The more important trace elements are sulfur (SO4--),
calcium (Ca++), phosphorus (HPO4--/H2PO4-), magnesium (Mg++) and iron
(Fe++).

Sulfur, calcium and magnesium are usually found in tap water. If the
water has too little general hardness (< 3 degrees dH), calcium and/or
magnesium may be in short supply. This can be remedied by adding
calcium and magnesium sulfate in small quantities.

Phosphorus can be measured in the water and should be present in
quantities less than 0.2 ppm of phosphate. If the nitrates are OK,
phosphorus levels are usually also OK.

Iron may be present in tap water in the correct ionic state (Fe++) but
will quickly oxidize to a form unusable by plants. To prevent this,
chelated iron mixtures can be used. The chelator prevents the iron
from oxidizing and makes it easy for the plants to assimilate. The
iron concentration should be less than 0.2 ppm.

Other trace elements are needed in extremely small quantities and can
usually be provided in fish food or specialized trace element
formulations. Note that some of these elements are toxic in anything
but trace amounts so the addition of trace elements should be done
very carefully.

OTHER INFORMATION

Some plants can concentrate carbon, potassium, nitrogen, phosphorus,
iron or the lesser trace elements and store it for later use. This
means that plants may do well for a while, using stored nutrients, and
then mysteriously wither if they can't replenish their supply. This
also means that some plants may "out-compete" others for required
nutrients, preventing the other plants from doing well.

Regular water changes are an important part of keeping a planted
aquarium healthy since many of the nutrients and trace elements are in
tap water. Changing 25 percent every two weeks is recommended.

The substrate can play a major role in the availability of nutrients.
Nutrients can be put in the substrate when an aquarium is setup by
mixing laterite (tropical clay), potting soil, peat moss or commercial
equivalents into the lower layer of gravel. These additives will
release some necessary elements and provide chelating sites so that
the correct ionic states are maintained. However, if nutrients aren't
replaced, the substrate will eventually be exhausted and the plants
will begin to do poorly.

If laterite or peat is used in the substrate and a very slow flow of
water can be forced through the substrate, water-born nutrients will
be chelated by the laterite or peat. This will provide a continuous
source of nutrients in the substrate. Substrate heating coils are
recommended for this since they can provide slow convection currents.
They are expensive, however.

The following table is based on data from the Feb, 1988 "Today's
Aquarium, the International Magazine of the Optimum Aquarium",
("Aquarium Heute" in German), published by Aquadocumenta Verlag GmbH.

Average nutrient content of plants and aquarium water

Notes: "mg/kg" and "mg/l" are roughly parts per million or "ppm"

"Concen Factor" is how much plants can store beyond their needs for
growth, i.e., plants can store 1000 times more iron than they need.

FAQ: Common Plant Listing

contributed by Erik Olson

The information on this page is collected from my own firsthand
knowledge, the plant list in the previous FAQ (author unknown), TAG
(further info indicated as volume:number), Aquarium Plants Manual by
Scheurmann (1993), various aquarium society bulletins, and old
articles on the Krib. Contributions by Elaine Thompson, Len Trigg,
Eric S. Deese, Shaji Bhaskar, and Peter Konshak.

Contents:

* Blacklisted Plants
* Explanation of Symbols
* Stem Plants
* Rosette Plants
* Ferns

Blacklisted Plants

These plants are so-called ``blacklisted'' because though they are
sold under the guise of being true aquatic plants, they are actually
land or emersed plants. Typically what happens is you buy one of
these, it lives for a month, then dies. Don't buy them, unless you are
setting up a paludarium and want to keep their leaves above water. The
main problem with identifying all the blacklisted plants is that they
are mostly known by goofy trade names which vary from
region-to-region... To make things worse, _true_ aquatics are
sometimes sold under one of these trade names as well, so it's best to
know the plant's scientific name!
* umbrella pine
* ground pines/club mosses (_Lycopodium_)
* aluminum plant (_Pilea cadairei_)
* crinkle (_Hemigraphis_)
* green hedge
* underwater palm
* spider plant (_Chlorophytum_)
* Chinese evergreen
* arrowhead -- either _Syngonium_ (the houseplant) or a species of
Sagittaria that doesn't do well submerged.
* pongol sword
* sandriana, green dragon plant (_Dracena sanderana_) -- tall
corn-like stalk, dark green sword-like leaves with white edges.
* mondo grass, fountain plant (_Ophiopogon japonicus_) -- Grassy,
leaves in one plane.
* Japanese rush (_Acorus gramineus_) -- looks like mondo.
* Brazil sword, Borneo swords _(Spathiphyllum sp.)_. _S. wallisii_
may be suitable for submersion according to Rataj.
* scarlet hygro/dragon flame/alligator weed (_Alternanthera_) -- see
stem plant listing as some varieties can be grown.
*

Legend

Most plants that grow under low or medium light will usually do even
better under higher light. Exceptions are noted. Here is what each
symbol means:
* [HIGH] High light requirement
* [MED] Medium light requirement
* [LOW] Low light requirement
* [HI pH] Tolerates brackish or high-pH water.
* [FAST GROW] Fast grower
* [FLOATING] Floating plant

Stem Plants

To propagate most stem plants, cut the stem and replant the top
cutting. You can also leave the bottom part (the mother plant)
planted, and it will sprout two or more new side shoots. Some stem
plants will grow out of the water (emersed) and produce flowers. Most
stem plants are suited for grouping as background plants.

Alternanthera (scarlet hygro, etc.) [HIGH]
Scarlet to deep red color, which turns olive in lower light
conditions. Usually the cuttings you buy have been grown
emersed, and will die underwater like a blacklist plant. (TAG
6:4, 6:5)

Bacopa (water hyssop) [MED]
A bog plant that grows OK underwater, background or filler
plant. Pale green-to-red fleshy leaves, up to 16" tall stem.
68-78F. Makes good background or side plant, in groups.

Cabomba (fanwort) [HIGH]
Stems up to 20" (50cm) tall. Leaves resemble fine pine needles,
fanning out from central stem. Pair of leaves at each node.
Will tend to break apart and litter the aquarium if light is
too low. Difficult to grow; needs high fertilization.

Cardimine lyrata [MED]
Beautiful, delicate plant. Small (1/2 - 1") heart-shaped leaves
with wavy edges on a thin stem. Grows roots above water at each
node. Tolerates cold water very well; will overwinter outdoors
at temperatures around freezing, even when emersed. Leaves look
kind of like _Hydrocotoyle sp._, but stem is straight.

Ceratophyllym demersum (hornwort) [HIGH] [HI pH] [FLOATING]
Very hardy. Whorls of forked leaves. Grows leggy under medium
light, quickly under better conditions. No roots, so can be
kept free-floating or planted. Lengths up to 2 feet.

Elodea/Egeria (anachris) [FAST GROW] [MED] [FLOATING]
Prefers low temperature (50-77F) tanks, somewhat alkaline pH.
Translucent green whorled leaves. Good goldfish food and tank
oxygenator. Can be kept free-floating or rooted. Nice beginner
plant.

Hydrocotoyle leucocephala (water pennywort) [HIGH]
Tall stem plant (over 20") with heart-shaped green leaves of 1"
diameter. Develops several small roots at each node. Tolerates
50-82F. Will grow floating when it reaches the top of the water
and flower in the aquarium. Doesn't root well, so needs to be
refreshed occasionally from cuttings. Leaves look kind of like
_Cardimine lyrata_.

Hygrophila corymbosa (giant hygro, temple plant) [HIGH]
Also known as _Nomaphila stricta_. Light green leaves,
sometimes with reddish veins. Easily grows out of the water,
where leaves turn dark reddish green. Big plant; makes good
corner/background in large deep tanks. Grows quickly given high
fertilization. Fairly hardy. Another species with similar
appearance and requirements is ``narrow-leaved hygro''
(probably _H. augustifolia_).

Hygrophila difformis (water wisteria) [MED]
Easy to grow. Prefers high light, but grows slowly under
medium. Fine branched light green leaves. Has different emersed
leaves, and flowers above water. Propagated from cuttings. Also
known as _Synnema triflorum_. Sometimes confused with water
sprite.

Hygrophila polysperma (green hygro, Indian hygro) [FAST GROW] [MED]
Spreads like a weed. Green under medium light, but gets
brownish tinge (and grows larger) in high light. ``Sunset'' and
variegated varieties are available, but harder to grow. (TAG
7:4)

Limnophila sp. (ambulia) [MED]
Similar in appearance to _Cabomba_, but less light-demanding.
Grows light green leaves in whorls at each node (_Cabomba_ has
a pair of leaves at each node). There are two common species,
_L. aquatica_ and _L. sessiliflora_. The former is larger, more
bushy, and has finer leaves. It is hardy in tropical aquaria
with high light.

Lobelia cardinalis
Similar/same the red-flowered land garden plant. Rumored to
leach poison if cut.

Ludwigia repens [MED]
Spade-shaped leaves, dark green to brownish colored. Stiff
stems, up to 20" (50cm) long. For me, transplant stems
sometimes rot.

Mayaca fluviatilis [MED]
Very pretty plant. Light green, narrow leaves about 1/2" long,
arranged in whorls. Attractive for background plantings. Became
commonly available in 1994. Like _Hygrophila_ species, it seems
to be a delicacy for fish. Doesn't root well, so plantings need
to be refreshed from cuttings.

Myriophyllum (water milfoil) [MED]
Temperate water plant that needs good lighting. Good for
background. Fine, green to reddish green leaves, depending on
the species. Produces coarser leaves above water, which will
flower.

Rotala [HIGH]
Very delicate leaves, easily damaged. Grows up to 20" tall, so
they make excellent background plants. _R. indica_ can grow in
medium light, but just will not stay as green. _R. macrandra_
is largest, and hardest to cultivate. It has red leaves with
pink undersides, turning to green in lower light, and requires
iron fertilization to maintain its red color.

Utricularia (bladderwort)

``Rosette'' Plants

These plants reproduce vegetatively (asexually) by runners or stalks,
which you can usually cut after the new plant is large enough to grow
on its own. Like stem plants, many will grow emersed and produce
flowers in that state. Generally, they prefer slightly-soft acidic
water (2-3dKH, pH 5.5-7).

Anubias [LOW]
72-82F (22-28C). Not really a rosette plant, _Anubias_ all have
a creeping rhizome that grows very slowly, throwing out new
leaves as it grows. The plant is built like a tank, some having
reported keeping them in a closet for six months in a plastic
bag yet still surviving. It is also one of the most expensive
aquarium plants. If grown emersed, they may produce larger
leaves, and will grow faster, and flowers will produce seeds.
Anubias will frequently flower underwater, but not seed. You
can grow the roots in gravel, or even train the rhizome to grow
on bogwood like Java fern does. (TAG 6:2) Most commonly kept
species is _A. barteri var. nana_, the smallest Anubias, which
has egg-shaped leaves and makes a great foreground plant in
medium-to-large aquariums. _A. barteri var. barteri_ looks
similar to the _nana_ variety, but with bigger leaves. _A.
congensis_, _A. lanceolata_ and others grow very tall and make
good background plants. They can sometimes be seen in better
stores.

Aponogeton [MED]
Tuber. Needs rest period (triggered after blooming? drops its
leaves), except for hybrid crispus. Easy beginner plant.
Foreground plant singly, or background in groups. Most species
flower by sending up a stalk with single or double-spike and
seed easily. (Grows very slowly from seeds, and you must
protect the young seedlings from fish.) (TAG 4:3) Oft seen
Species:

+ bouvianus
+ crispus: up to 20" (50cm) tall, red to green leaves; easy
starter plant, often sold as bulbs at Wal-Mart. Single-spike
flower stem, slightly-undulating leaf margins.
+ elongatus,
+ ulvaceus: 10-20" (25-50cm) wavy light green leaves,
twin-spiked flower.
+ undulatus: 16" (40cm) slightly-undulating leaves, smooth in
low light. Flowers rarely.

Aponogeton madagascariensis (Madagascar Lace Plant) [HIGH]
Very desired plant because of its 6-18" leaves which are
actually a lace-like skeleton. Pink self-fertile flowers on
double-spiked stalk. Likes rich substrate. Observe dormancy
period! Dies in water over 80F. Difficult plant to grow.

Barclaya longifolia (orchid lily) [HIGH]
10-20" (25-50cm) delicate brownish or olive-green leaves,
moderately-undulated margins. Likes warmed substrate and warm
aquariums (75-82F). Foreground single plant. Often rots on
transplant. Flowers and seeds easily by sending a stalk to the
surface, or will remain submerged and closed (seeds still
viable). Very difficult to grow. (TAG 4:1).

Crinum (``onion bulb'') [MED]
As the name implies, it grows from a bulb and looks like a
scallion. Bright-green leaves are huge 20-40" (50-100cm), and
recommended only for large aquariums. Does better in bright
light.

Cryptocoryne [LOW] (most species)
Shocks on transplant, takes up to months to adjust to new tank,
so don't move them once you've planted them. Crypt rot caused
by sudden water chemistry/quality changes. Spreads by rhizome;
new plants develop at nodes. -> Not a good beginner plant.
Often sold potted in rockwool, which reduces the above shocks.
Usually prefers acidic water. Some species will not tolerate
high light. Requires iron fertilization and likes rich
substrate. (TAG 4:1, 4:2, 5:1, 5:2, 5:3, 5:4) Oft-seen species:

+ affinis: emerald-green 4-12" (10-30cm) leaves, red
undersides. Foreground plant in large aquariums or center
plants in small tanks. Grows OK in alkaline water.
+ balansae: likes higher light?
+ becketii: likes higher light?
+ lutea: easier crypt to grow.
+ walkeri
+ wendtii: easier crypt to grow. bronze, red, green varieties.
wrinkled leaves. Up to 8" tall. Adaptable to high light and
will grow with CO2.

Echinodorus (Amazon swords) [MED]
Most are good as single highlight plant, or background groups
in large aquariums. Like high levels of fertilizer. Can grow
emersed. Reproduce by adventitious plants on end of stalks
runners, or root division, depending on species. (TAG 4:5, 5:5,
7:1, 7:5) Common species:

+ bleheri, paniculatus, amazonicus: Your generic amazon swords,
usually available in small, medium or large. Light green
leaves can be over 20" (50cm). Produces plantlets directly on
the flower stalk.
+ cordifolius (radican sword): heart-shaped leaves. Likes being
emersed; will flower in open-top aquarium. Sends floating
leaves if illumination is low.
+ major/maior (ruffle sword)
+ osiris (melon sword): blood-red slightly-undulate leaves.
+ parviflorus (tropico sword): smaller variety.
+ tenellus, quadricostatus (pygmy chain sword): leaves up to
6", 72-86F. Fast reproduction by runners; can create a lawn
on large enough tank. Small plants; nice foreground display.

Lemna (duckweed, green plague) [FLOATING] [FAST GROW]
Tiny (1/4") plant with a pair of leaves and a root. Reproduces
very quickly. A very noxious weed, hard to eradicate, and most
fish don't like to eat it. Try a floating fern such as
_Salvinia_ instead of this one.

Lilaeopsis novae-zelandiae (``micro sword'') [HIGH]
64-77F. This plant sold under this name is probably _L.
braziliensis_, a South American _Liaeopsis_. It slowly spreads
out in thick "turf" of grass, about three 1-3" long light green
grass-like leaves per plant. Nice spawning medium, foreground
plant.

Nuphar (spatterdock) [HIGH]
Water lily-like plant. Usually sold as rhizome end-cutting,
which rots away in a month. Likes colder temperatures.

Nymphaea (Water Lily, tiger lotus) [HIGH]
Bulb. Delicate leaves, colors varying from red to green with
possible mottled spots, depending on the variety. Pinch off
floating leaves if you want only submerged ones. Reproduction
is by blooms, or side-tubers from the main bulb. Need 3-5
floating leaves for it to bloom.

Nymphoides aquatica (banana plant) [HIGH]
Olive-colored Heart-shaped leaves that look superficially like
water lily, and banana-like tubers on roots. Plant by sticking
the tubers 1/3 in the gravel. Prefers lower temperatures.
Throws out floating leaves if light and fertilization is good.

Pistia stratiotes (water lettuce) [HIGH] [FLOATING]
Very demanding plant that prefers full sun (where it will grow
the size of actual lettuce) over aquarium conditions (where it
might be the size of a quarter). Reproduces by runners. Buy at
water garden supply stores.

Sagittaria (sag, arrowhead)
Straight-bladed green grass. Many different varieties, some
small foreground plants, some rather big. Hardy. Propagates by
runner. _S. subulata_ grows 4-24" leaves and throws up small
white flowers in shallow water. 63-82F.

Valisneria [MED] [HI pH]
Grass. Reproduction by runners. Some find it grows wildly, then
mostly dies off, in a cycle. Wide temperatures 59-86F. _V.
spiralis_ (Italian val) has ribbon-like leaves up to 20" (50cm)
and throws up a spiral stalk when flowering. _V. tortifolia_
grows ``corkscrew'' leaves, hence its name Corkscrew val. Other
common species: _V. gigantica_ (Jungle Val).

Wolffia (watermeal)
Similar to duckweed (_Lemna_), but even smaller.

Ferns and Mosses

Azolla (floating fern) [HIGH] [FLOATING]
Floating fern that grows out in triangular ``rafts''. Buy at
water garden stores.

Bolbitus heudelotii (African water fern) [LOW]
Slow-growing creeping rhizome with dark green, 8" (20cm) lobed
leaves. Tie roots to bogwood like Java fern. Don't bury the
rhizome in the gravel. Can be grown emersed with fast-moving
water.

Ceratopteris (water sprite) [LOW] [FAST GROW] [FLOATING]
Up to 20" (50cm) tall. Exists as rooted or floating specimens.
Good fry shelter, shade plant. Baby plants grow on older
leaves. Confused with _Hygrophila difformis_ sometimes. Several
different species and/or forms, which may require more light
than others.

Microsorum pteropus (Java fern) [LOW] [HI pH]
``It's actually _Microsorum_ but everyone writes it as
Microsorium,'' says Arie De Graff (FAMA, 1991). This is one of
the more hardy aquarium plants. It roots itself to solid
objects like bogwood and rocks (attach with a piece of string
or rubber band to hold it in place at first) and has a creeping
rhizome which may be divided for cuttings. Young plants will
also develop directly off spores, attached to old leaves, and
can be cut off and rooted. In high light, it produces tough,
plastic-like leaves; under low light the leaves are more
delicate. Fronds are up to 8" (20cm) long and undivided, though
on older plants are trilobade (three lobes to a frond).

Riccia fluitans (floating liverwort, crystalwort) [MED] [FLOATING]
Big tangly glop like Java moss; good livebearer fry cover.
Grows fast under high light.

Salvinia (floating fern) [FLOATING]
Small floating fern that grows in long chains of two oval
leaves and a ``root-like'' third leaf. Easier to control than
duckweed. Buy it at water garden supply stores, as it's too
cheap for most aquarium shops.

Vesicularia dubyana (Java moss) [LOW]
Grows in branching strands, tangling around other plants. Dark
green. Makes good spawning medium and cover for young fry. Min
temp 75F. May dislike salt.

FAQ: Lighting

author unknown

All plants have a cycle in which during the light hours they use CO2
and release Oxygen through a process called photosynthesis. During the
dark hours the opposite occurs and the plants use Oxygen and release
CO2 in a process referred to as respiration. In most aquarium plants
the period of photosynthesis in nature is between 10 and 12 hours
which should be duplicated as closely as possible in the aquarium to
allow a balance between the two processes.

In nature some plants are located in large open ponds and receive a
large quantity of light, others are located in triple canopy jungles
and receive low quantities of light. Each variety of plant has its own
light requirements and for best aquarium results these requirements
should be met as much as possible. In this FAQ we will divide the
plants into groupings that require low light, low to moderate light,
moderate to bright light, and bright light. There are also bog plants
that are often sold as aquarium plants which we shall not cover in
this FAQ except to mention here that their lighting requirements are
usually greater than even the bright grouping.

Fluorescent lighting is the most economical means of establishing a
broad spectrum of light in an adequate quantity for the survival of
aquatic plants. It is recommended that broad spectrum tubes be used to
produce the proper lighting similar to the varieties sold in plant
stores and aquarium stores, rather than the standard cool white bulbs
available at hardware stores. People have had good luck with almost
any of the "full spectrum" or plant specific bulbs (Vita-Lite, GE
Chroma 50 and 75, Phillips Agro-Lite, UltraLume and Advantage X). The
more expensive "three phosphor" bulbs like Triton and Penn-Plax
Ultra-TriLux seem to have a more realistic color rendition. You can
combine different types of bulbs to achieve the same results but the
tri-phosphor bulbs are generally much brighter than less expensive
types. Note that fluorescent bulbs age and will lose intensity over
time. It is recommended that bulbs be changed every 6-12 months (try
to have the bulbs on a rotating schedule, i.e., a new bulb every 3
months rather than 2 new bulbs every 6 months).

When calculating the amount of lighting you will need there is a
general of thumb. First multiply the surface area of the aquarium by
the distance from the light source to the top of the gravel. Then
depending on the type of plants you desire multiply this by one of the
factors given below.

Low light plants 0.08
Low to Moderate light plants 0.12
Moderate to Bright light plants 0.18
Bright light plants 0.27

This will give you the ideal watt hours of fluorescent lighting that
you need. Divide this number by 11 and you now have the approximate
total wattage of lights you need. Unfortunately this number may not be
equal to what is available in bulbs so find the combination of wattage
that will most closely match this requirement and adjust the available
time to match the watt hour calculation.

_Example_: required watt hours is 1440, divided by 11, is 131 watts of
power. since the closest is 3, 40 watt tubes we divide 1440, by the
120 watt total and we find we need 12 hours of lighting at this level.

_Warning_: A common mistake is to deviate greatly from the 11 hours of
light to compensate for low or high wattage. If the light time exceeds
16 hours more wattage should be added to reduce this time, Or if the
light time is less than 8 hours less wattage must be used to allow
adequate time for photosynthesis.

When selecting plants also keep in mind that large center plants will
shade the smaller plants under them and that higher light requiring
plants should not be selected for small filler plants.

Converting a fluorescent fixture to auto-start

Many older or cheaper fluorescent fixtures require you to hold down a
pushbutton for a few seconds to turn it on, thus preventing you from
plugging it into a timer. You can convert such a fixture into an
auto-starting model by clipping two wires and buying two new parts.
You need a _starter_, a little gray can-like thing found in any
hardware store. Make sure to buy the correct one for your size bulb;
they say which is right on the package. You also need to buy a socket
for the starter, or find some way to attach the wires directly to the
two terminals on the starter. The sockets can sometimes be
hard-to-find, but big hardware stores might have them, and mail-order
fish suppliers (MOPS, for instance) can sell you both parts as a kit.
Refer to the diagram below (contributed by Hardjono Harjadi):

line switch line plug
\ Hot wire /-----|
+------------ballast-------------o \____________/ |--- -> smaller plug
| --\ |----- -> longer plug
| --------- | \-----|
| ----------------|starter|---------------+ +-----------------------+
| | --------- | |
| | +---------------------+ |
| | | |Neutral
| | |-----------------------------------------------------| | |Wire
| +---| |---+ |
| | light tube | |
+------| |--------+
|-----------------------------------------------------|

The two leads you want to connect to the starter are connected to the
pushbutton; usually they're red. Clip them at the pushbutton and
attach to the starter socket. That's all!

FAQ: CO2 in the aquarium

author unknown

Anyone who has observed the explosive growth of aquarium plants in
response to carbon dioxide (CO2) fertilization must be convinced of
the usefulness of this system. Certainly, there are thousands of
aquarium hobbyists who do not give their plants any sort of special
treatment and still end up with a fairly nice display. However, truly
luxuriant growth, the sort that you see on the covers of aquarium
magazines and in pictures of "Dutch aquariums," can only be achieved
by fertilizing with CO2.

During photosynthesis, plants use light energy to capture CO2. This
CO2 is used to build the basic carbon structures from which all plant
material is made. In a poorly lit aquarium, light is likely to be what
limits the rate of plant growth. The amount of CO2 produced by fish-
and bacterial respiration is more than enough to allow photosynthesis
under these conditions. If on the other hand, you try to make your
plants grow faster by adding more light, it is likely that there will
not be enough CO2 in your aquarium. The plants simply can not grow as
fast as they would like to, given the available light energy.

The easiest way to increase the amount of CO2 in an aquarium is to buy
a tank of CO2 and let it bubble into the water. Several, mostly
German, companies sell systems for adding CO2 into the outflow of your
canister filter. If you buy your CO2 system from someone like Dupla,
you are likely to spend about $300. That seems a bit pricey, doesn't
it? Fortunately, it is very easy and also a fair bit cheaper to buy a
CO2 tank at a local welding supply place and use it to bubble CO2 into
the water.

CO2 in the tank is under high pressure. A pressure regulator brings
this pressure down to a manageable level, and ordinary aquarium air
valves can be used to regulate the flow to individual aquariums.
[Editor's note: this is counter to general net-experience. Most of us
end up installing a fine-metering needle valve after the normal
regulator in order to regulate the flow down to a few bubbles per
second, because normal aquarium air valves do not have good enough
control.] The CO2 reactor is simply a small chamber that allows the
CO2 to be dissolved in the water before it escapes into the air.
Outflow from a filter or a pump enters the top of the reactor; CO2 is
bubbled in from the bottom. To give the CO2 more time to dissolve, one
can add a system of baffles to trap the gas as it is moving up. Near
the top of the reactor, there should be a small hole to vent other
gases, which may be present in small amounts in the compressed CO2.
These gases do not dissolve as readily in water as CO2 does.

I purchased my CO2 tank and regulator at Wesco on Vassar Street in
Cambridge. Their current (May 1992) prices are: 5 lbs CO2, $52.50,
refill $9.74; 20 lbs CO2, $101.75, refill $19.55. A CO2 pressure
regulator is "$79 and change." People who have better welding
connections than I do might be able to get things more cheaply than
that. [Editor's note: look in the PLANT RESOURCES section for more
current prices and good inexpensive sources.] Refills are generally
not a very big expense. My 20 lb CO2 tank is used on three aquariums
(30, 65, and 110 gallons) and lasts about three years between refills.
That works out to about $2 per aquarium per year. Other possible
sources of CO2 that I have not investigated are CO2 fire extinguishers
and the CO2 canisters they use to put the bubbles in beer and soft
drinks. Don't bother trying to rig up something with dry ice, it is
too complicated.

The tubing and valves that I use for my CO2 setup are the sort that
one buys for use with the aquarium air pumps. It is better to get the
brass rather than the plastic valves, since it is easier to make fine
adjustments with them and they also tend to leak less. Even a tiny
leak can empty out a gas tank distressingly quickly. I check all of my
valves and connections with a soap solution and make sure that no
bubbles appear.

The CO2 reactor can easily be constructed out of any wide bore tube. I
use the lift tubes from an undergravel filter in my aquariums. Local
aquarium enthusiast Jim Bardwell does well with the top half of a
one-liter coke bottle, with the filter hose attached to where the cap
should be. It is best to use a clear plastic, so that one can see what
is happening inside. Baffles, designed to let the water cascade down
in one direction and to trap the CO2 moving in the other direction,
are helpful, but not absolutely necessary. I make my baffles out of
foam cubes that I cut to the right size and shape to fit inside the
tube. Jim simply lets the CO2 collect at the top of the reactor, where
the water is coming in. He does not have a vent and does not seem to
have a problem with excess gas accumulating.

While a small increase in the amount of CO2 in the water causes lush
plant growth, too much CO2 can prove to be toxic. CO2 dissolved in
water forms carbonic acid (H2CO3). With weakly buffered water, like
what comes out of the tap in the Boston area, adding too much CO2 can
bring the pH down to as low as 3. That is not quite as acidic as Coca
Cola, but about equal to vinegar. Naturally, this can cause death or
other serious reactions in your fish and plants.

One can buy CO2 test kits that measure the actual level of CO2 in the
water, but measuring the pH and counting the bubbles in the CO2
reactor works just about as well. It is best to start off by adding
CO2 very slowly (about one to three bubbles per minute) and increasing
the rate until a small, but measurable drop in pH is achieved. In my
30-gallon aquarium, I add one bubble of CO2 every three to four
seconds to bring the pH from 7 to between 6 and 6.5. How much CO2 one
needs to add varies from aquarium to aquarium and can depend on
several factors: the size of the aquarium, how fast the plants are
growing, the number of fish, how much food is decaying on the bottom,
the buffering capacity of the water, the types of rock and gravel, and
how well ventilated the surface of the water is. However, anything in
the range of one bubble every two to fifteen seconds seems to work
pretty well. Bubble size will vary with the diameter of the tubing. I
am referring to the sort of bubbles that come out of the end of
ordinary, one eighth inch inside diameter aquarium air tubing.

By using a CO2 reactor, you are saturating the water with CO2, and any
excessive agitation of the water surface or bubbling of air through
the water will cause the CO2 to escape into the atmosphere, just about
as quickly as you can add it. Thus, at least during the day, you
should *not* have an airstone or an undergravel filter turned on. If
you have a plant aquarium, you should probably not be using an
undergravel filter, anyway, since most kinds of plants do better
without one. When the lights are on, plants use CO2 and produce
oxygen. In my tanks, so much oxygen is being produced, that I can
often see it forming streams of bubbles from the plants. At night, on
the other hand, the plants are actually using oxygen (and not CO2) If
there are not too many fish in the aquarium, then the oxygen produced
by the plants during the day will tide everyone over until the next
morning. However, if you notice that your fish are gasping at the
surface in the mornings, they are obviously running out of oxygen. To
remedy this problem, you can simply turn on an air stone when the
lights go out. This will keep up the oxygen level and remove excess
CO2. I have the aquarium lights and an air pump on two separate
timers; when one turns on, the other one turns off. It would also be
fairly easy to rig up a solenoid valve for the CO2 supply and have it
turn the CO2 on and off with the same timer that is regulating the
lights.

The system that I have described here and use is a very basic one that
works well. For those who like those sorts of things, the automation
possibilities are almost limitless. My brother Albrecht, who is an
electronics whiz, has his entire aquarium run by a TRS-80 computer.
Among many other things, the computer measures the pH, adds more CO2
if the pH is above a predetermined level, and sounds an alarm if the
CO2 tank is running low. Fortunately, you don't need all of that to
have a truly great-looking plant tank. There are more than thirty
kinds of thriving plants in my aquariums; I have to weed out bunches
once a week, and I have enough extras to supply all of my aquarium
friends and still sell some at the monthly BAS auction. The fish are
also doing well and reproducing.

CO2 makes it easy to grow aquarium plants, but it is not a cure-all.
You still have to observe some of the other essentials of proper plant
care. Aquarium plants need a lot of light. When using fluorescent
bulbs, I usually figure about four watts per gallon. Wide-spectrum
plant and aquarium bulbs seem to work better than the "soft white"
ones that you can buy at the hardware store. The amount of iron in
most aquariums is too low for maximum plant growth. I supplement the
iron by adding "Micronized Iron" to the canister filter (about one
teaspoon at every cleaning) and "Ortho Greenol" directly to the water
(two drops per ten gallons per day). Both of these are available at
gardening stores. Other nutrients and trace elements that your plants
need are usually taken care of when you feed the fish and do water
changes (frequently). Also, don't forget the regular sacrifices of
goat entrails to the aquarium gods, at midnight when the moon is full.

FAQ: Substrate Heating Cables

contributed by George Booth

Much of the mystery surrounding heating cables is that Dupla has been
careful to hide the rationale to protect their product, i.e., keep it
"magic".

I think a key concept is that we are NOT trying to mimic what happens
in nature (even though the Dupla description implies that) but we are
trying the achieve an equivalent biological affect.

In nature, you have sources of underground water moving to the surface
or surface water moving to aquifers due to natural pressure
differentials. Dupla mentions this in terms of "nutrient springs" in
tropical streams. In our aquariums, there are no such natural
pressures to cause any movement (except for UGF, etc).

The water column will tend to keep the gravel at water temperature
through conductive heating; heat will "seep" downward. However, in
glass tanks especially, the glass bottom is radiating heat into the
room, cabinet, etc, unless insulation is provided. This will tend to
keep the roots cooler than the water temperature. Even with
insulation, you'll find the bottom of the substrate cooler than the
top, just not as much.

Here is a list of substrate processes I think are important (no
particular order of importance implied):
1. Provide warmth in the substrate for certain plant species
(_Barclaya longifolia_, specifically). In this case the substrate
should be warmer than the water. (``hot feet'')
2. Provide warmth in the substrate to speed up biochemical processes.
3. Transport nutrients from the water into the substrate. Important
nutrients would be ammonium (fish waste, etc), iron (from trace
element additions), calcium, potassium and other trace elements.
This will replenish nutrients used by the roots and provide long
term viability (in terms of years).
4. Transport harmful products out of the substrate. Decomposition
products may be harmful to plant roots. There is also conjecture
that plants give off low level toxins to keep other plants out of
their territory (successful weeds have made this an art form). If
these toxins build up due to poor circulation, the plant may harm
itself.
5. Provide a chelating medium that binds the divalent state of trace
elements with an organic molecule, enabling the trace element to
be adsorbed by root hairs.
6. Provide a reducing rather than oxidizing environment so that trace
elements are kept in their divalent state (usable by plants) or
are reduced from their oxidized trivalent state. Iron especially
will rapidly oxidize in water with normal levels of oxygen.

_Heating coils_ provide the ``hot feet'' and warmth for biochemical
processes directly. The convection currents generated by the "spot"
heat source of the coils provide for nutrient and toxin transport.
Laterite in the bottom 1/3 of the substrate provides the chelating
medium. The slow convection currents, coupled with nitrifying bacteria
in the gravel will reduce the concentration of oxygen getting to the
bottom layer of the gravel, providing a reducing environment.

A _heating pad_ under the tank will tend to warm the entire bottom
layer uniformly. This will provide hot feet and increased biochemical
activity, but I suspect the heat will go through the gravel as
conduction and _won't generate convention currents_. Thermodynamics
theory says that conduction will occur up to a certain heat threshold
and then convection currents will be formed with more heat. I think
the linear hot zones generated by proper spacing of the coils along
with the higher temperatures of the coils will provide this. Yes,
there will be hot and cool zones for the roots but I think the other
factors outweigh this.

Schemes that use warm water flowing in tubes in the gravel (Bioplast,
for example) won't work, IMHO, because they can't generate enough
heat. Bioplast wraps some tubing around a heater and pipes it through
the gravel with a pump. The first foot or so of the tubing may get hot
enough (though I doubt it) but the water in the coil will cool off
rather quickly as it travels through the tube. If the tube is
insulated enough to keep the water hot, then it won't transfer any
heat to the gravel.

Reverse flow undergravel filtration (RUGF) will provide increased
biochemical activity, toxin transport, and a reducing environment. It
may provide ``hot feet'' if you heat the water before putting it
through the RUGF. Nutrient transport is kind of difficult since the
water is usually filtered before going to the RUGF (to avoid injecting
crud into the gravel) and trace elements probably will be oxidized in
the filter (oxidizing is a bio-filter's purpose). Chelating is a
problem because a RUGF will probably push the laterite up and out of
the gravel. Don't get me wrong, a RUGF _may_ provide the six
processes, but it would be difficult to get it set up with the right
flows and even flow across the substrate and proper mechanical
filtering, etc. A coil setup is a "no-brainer" if you have the correct
wattage.

UGF will provide warmth for biochemical activity, and nutrient and
toxin transport. Hot feet would be very tricky to achieve, if not
impossible. Detritus pulled into the gravel can be chelated by the
substrate, but a reducing environment is almost impossible unless a
very slow flow is used and that would be hard to do evenly across the
whole substrate.

We have three ~100g tanks with coils and one 85g tank with UGF. All
grow plants equally well but the 85g is much more unstable. We think
it is sensitive to too much detritus building up in the gravel; a
thorough vacuuming every 6-9 months perks it up. The coil tanks
require no gravel vacuuming and the 90g tank was rock solid
biologically for at least three years. We replanted at that point
because some of the plants had gotten out of control but we didn't
"tear down" the tank - just replanted.

I think this is the key to the cables - long term stability. Plants
will grow fine without them if you can accomplish most of the six
things I mentioned. Just pulling up plants for trimming every month
will accomplish as lot (stirring up the gravel, moving roots out of
their toxin zone, etc).

Construction

Fully-automated systems can be purchased from commercial sources such
as Dupla, though the cost can be a bit much for a beginner. You can
save a great deal of money by buying just the cables and building the
rest of the setup yourself. If you use a small enough wattage cable as
a _supplement_ to your tank's main heater, the temperature controller
can be ignored or replaced with a timer, requiring only a low voltage
transformer! Furthermore, it is possible to make your own cables,
taking the price down almost to that of a ``normal'' heater.

Resources for Aquatic Plants and Related Items

last updated May 1995

This section contains mail-order sources for much of the plant-related
items discussed elsewhere. They are all listed here so this section
can be kept up-to-date without the bother of changing the others. Oh,
one more thing, these are United States sources, and will probably be
useless to the rest of the world (feel free to volunteer info for
other countries, and we will try to add it).

Siamese Algae Eaters

The Siamese Algae Eater, _Crossocheilus siamensis_, the only fish
known to eat red algae, is not generally available in the United
States. George Booth located a source in California that imports them
directly, but they do not seem too happy to ship them around the
country anymore. Still, you might try asking.

Contact:

Glenn Zappulla
Albany Aquarium
818 San Pablo Ave.
Albany, CA 94706
(510) 525-1166

Mail-Order Plants

_Delaware Aquatics Imports_
18 Anderson Road
Newark, DE 19713
302-738-4042

Hard to reach Mike, the owner, during the day; try calling in the
evenings.

_Aquarium Driftwood_
PO Box 91491
Mobile AL 36691
phone 334-345-2323
http://www.pair.com/aqwood/index.htm

``I've ordered from them several times. The first two were great the
third some of my plants got cooked but I believe that is just becouse
I live in AZ and they were shipped in the summer. And it's just hot in
the summer in AZ.'' -- Rhonda Wilson <7603...@compuserve.com>

Please send names of your favorite supplier; this section could be
expanded. Also see the MAIL ORDER POND SUPPLIES in the main FAQ
resource section.

CO2 Supplies

You can get many of the supplies for building your own CO2 injector
from local welding shops and carbonated beverage distributors. Some of
the equipment has been found particularly inexpensive:
* Cylinders: (This comes from Matt McCabe) One cheap source is Geer
Gas in Ohio, $38.50 for a 5lb cylinder, plus big shipping. It's
still cheaper than buying it in some places. 1-800-696-4337
(614-464-4277). Refill at fire extinguisher store or beverage
supply house.
* Regulators: (Information from George Booth and Erik Olson) While
waiting for my CO2 tank to be refilled at the local welding supply
shop, I was browsing all the cool stuff related to the welding
profession. Mixed in amongst the plaid caps and kinky leather face
masks was a "FROG" - Flow Regulated Orifice Gauge. It is a preset
regulator for CO2 tanks that is set to 22 PSI. It has a little
button that either pops out or retracts when the tank is almost
empty (but does not function very when used with the low flow
rates in aquaria). This would be an inexpensive way to get setup
with a more capable CO2 system. It was marked $22 and is made by
Western (Model RP22320). You can call Western directly at
216-871-2160 to find a local distributor.
* Needle Valves: (from Gary Bishop) ``$9.60 from "Air Power Inc."
(In Yellow Pages under Valves). This valve is the model "NO1" from
"The ARO Corporation, One ARO Center, Bryan, OHIO 43506, Phone
(419)636-4242". It provides infinite control from full-close to
full-open. It has a neat color scale to indicate the degree of
openness and can be locked at any setting. The adjustment is very
smooth; I can go from off through incredibly slow flows to just
right and beyond to way more than I need. You can locate a
distributor of this valve in your area by calling the ARO company.
Even if you cannot locate this exact valve, your local dealer
might be able to suggest an equivalent substitute of a different
brand.''
* Solenoid Valves: (from Gary Bishop) ``$24.00 from "Air Power Inc."
(In Yellow Pages under Valves). This is solenoid valve model
"CAT33P-012D" from "The ARO Corporation, One ARO Center, Bryan,
OHIO 43506, Phone (419)636-4242". You can get it with a variety of
coil voltages. I chose 12 volts DC.''

Dupla

Dupla supplies CO2 equipment, fertilizers, and heating cable systems,
among many other nifty expensive specialty products. In the US, Dupla
is imported through J.P. Burleson and Company, but they do not sell
directly to the consumer. You can either bug your local retailer to
special-order something for you or purchase through a mail-order
company. Two popular mail-order house are DaleCo and Pet Warehouse.

Sandpoint

Sandpoint sells pH and other controllers. Top-of-the-line, but also
very expensive. Must order from a dealer.

Aquatic Plants E-Mail List

(This came from Shaji Bhaskar) The aquatic plant mailing list is
intended to be a medium for exchange of information about all aspects
of growing aquatic plants as a hobby. Postings on both aquarium plants
and pond plants are welcome. Topics of discussion include (but are not
limited to):
1. Individual plant species (identification, cultivation,
propagation, etc.)
2. Aquascaping
3. Substrates - pros and cons of commercial substrate additives,
potting soil, peat, etc.
4. Water conditioners and fertilizers
5. Hardware - heaters, filters, surface skimmers, etc.
6. Compatibility of fish and other organisms with aquatic plants
7. Trades/exchanges between hobbyists (advertisements from
commercial-scale operations are not permitted.)

To subscribe, send the following in the body (not subject line) of an
e-mail message to ``Majo...@actwin.com'':

subscribe aquatic-plants

Aquatic Gardeners Association

``Purpose of the AGA:
1. disseminate information about aquatic plants
2. to study and improve upon techniques for culturing aquatic and bog
plants in aquariums and ponds.
3. to increase interest in aquatic gardening
4. to promote fellowship among its members.

The journal of the AGA is called _The Aquatic Gardener_ and we put out
6 of these a year. The publication is usually 25-30 pages long and
contains good info. Membership dues are $15.00yr, U.S./Canada/Mexico
and $28.00/yr, all other countries.

Send check or money order to

Dorothy Reimer (Membership)
83 Cathcart St.
London, Ontario
CANADA N6C 3L9

(All funds must be in U.S. Currency)

AGA is a non-profit organization.

Books

(This list originally came from George Booth)

Plant basics

* _Aquatic Plants; Hobbyist Guide to the Natural Aquarium_
Aquarium Digest International #45
Andrews, C.
Tetra Press
* _Hobbyist Guide to the Natural Aquarium_
Andrews, C.
1991, Tetra Press
* _A Fishkeeper's Guide to Aquarium Plants_
James, Barry
1986, Salamander Books Ltd., London.
``Lots of people recommend this as a great first plant book.'' --
E.O.
* _Water Plants in the Aquarium_
Scheurmann, Ines
1987, Barron's Educational Services
* _Aquarium Plants Manual_
Scheurmann, Ines
1993, Barron's Educational Services
``Lots of detail and good photographs for a small book. Well worth
the price.'' -- E.O.
* _The Complete Book of Aquarium Plants_
Allgayer, R., and Teton, J.
1987, Ward Lock Limited, London.

Plant Identification and Culturing

* _Aquarium Plants, their identification, cultivation and ecology_
Rataj, K., and Horeman, T.
1977, T.F.H. Publications, Inc. Ltd.
``Somewhat disorganized and out of date, but readily accessible to
any hobbyist. Says something about virtually every plant.'' --
E.O.

Technical Setup, Equipment and Maintenance

* _The Optimum Aquarium_
Horst, K., and Kipper, H.
1986, AD aquadocumenta Verlag GmbH.
``The bible for anyone interested in high-tech planted tanks.'' --
E.O.

Web and FTP Sites

More detailed information on plants and planted tanks can be obtained
from ``the Krib'' World Wide Web pages
(http://www.cco.caltech.edu/~aquaria/). A text snapshot of most of
this is available on the aquaria archive
(ftp.cco.caltech.edu:/pub/aquaria) under the ``freshwater/Plants''
subdirectory.

End of Plant FAQ.

Aquaria Robot

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