Light colors
Kristin Caufield
Hello,
I am desperately trying to get plants to grow in my tanks, and after
oodles of research, I am going try again with better success. Job one,
getting new bulbs -- mine are all at least a year old. I currently have
aqui-lux bulbs on my tanks, and love the blue coloration it gives off.
It makes my neons glow wonderfully, in a way the pink plant bulbs can't.
I was looking at getting a "fancier" bulb, however, I am not to sure on
how to read the colors via the FAQ pages (i.e. Kelvin) to find a similar
range. I was considering a Triton bulb, but I heard that they tended to
be more pink than violet. There is also the Beauty light that seems to
be similar in function, however I have found no schematics on what color
ranges this bulb runs.
Thanks for any information
Kristin Caufield
KJCau...@UCDavis.edu
Erik Olson
Kristin Caufield <kjcau...@ucdavis.edu> writes:
>Hello,
> I am desperately trying to get plants to grow in my tanks, and after
>oodles of research, I am going try again with better success. Job one,
>getting new bulbs -- mine are all at least a year old. I currently have
>aqui-lux bulbs on my tanks, and love the blue coloration it gives off.
>It makes my neons glow wonderfully, in a way the pink plant bulbs can't.
>I was looking at getting a "fancier" bulb, however, I am not to sure on
>how to read the colors via the FAQ pages (i.e. Kelvin) to find a similar
>range.
I'm noting this so when the Lighting FAQ is improved next month it
will include color temp info! Here is some info:
Basically, the higher the temp, the more bluish, the lower the temp,
the more reddish. The sun has an average color temp of 5700K.
Incandescent bulbs have a temp of 3200K, which is why most fluorescent
lighting is also around 2700K-4100K. You can get inexpensive 5000K
bulbs at Home Depot and other places as "Chroma 50" (aka "Sunshine"),
"Design 50", "Daylight", etc., for around $5 per tube. You can also
get Chroma-75's which are 7500K balanced (and thus more blue).
Color temperature means much less in bulbs that do not have a similar
spectrum to the sun (i.e, X amount of red, Y amount green, Z amount
blue, etc... this is an oversimplification, but hey!). For instance,
aquari-lux, and Gro-lux bulbs have a weird distribution including lots
of red (and in the case of Gro-lux, purple). The degree of similarity
to the sun's spectrum is called color rednitioning index or CRI. And
it's the CRI that you pay for when considering the differences between
a Chroma-50 (75 CRI?) and a VitaLite (95+ CRI?). The sun has a CRI of
100.
It has been the general conclusion of folks here that CRI (and for
that matter, color temperature!) does not affect plant growth very
much; this mainly is important for the humans viewing the tanks. The
most important factor for plants is the INTENSITY! 2-4 watts per
gallon (for most tanks using fluorescent lights, though your actual
mileage may vary).
- Erik
--
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Erik Olson
eriko at wrq.com
Humanoid 5
>From: er...@wrq.com.nospam (Erik Olson)
>It has been the general conclusion of folks here that CRI (and for
>that matter, color temperature!) does not affect plant growth very
>much; this mainly is important for the humans viewing the tanks. The
>most important factor for plants is the INTENSITY! 2-4 watts per
>gallon (for most tanks using fluorescent lights, though your actual
>mileage may vary).
This seems a bit wasteful though in terms of trying to run our tanks with the
most efficient use of energy. From what I've gathered doing research into reef
tank setups, there is a peak of photosynthesizing activity at around 420
nanometers wavelength - well into the blue end (which is genetically logical
since since blue penetrates water farther than red). There is another peak at
the red end, I forget the number now. The "ideal" bulb would hava a peak in
one or both of these ranges, and then add something for us humans to see with,
using the least amount of watts possible. So far, metal halides look to be the
best solution. Any other suggestions?
Poseidon
What's up, er...@wrq.com.nospam (Erik Olson), you wrote in
rec.aquaria.freshwater.plants:
>a Chroma-50 (75 CRI?)
Actually 90CRI.
______________/Poseidon\________________
You know what to do. Kill the .removethis
Nestor10
I have to point out something here -
> From what I've gathered doing research into reef tank setups, there is a
peak of photosynthesizing activity at around 420 nanometers wavelength -
well into the blue end (which is genetically logical since since blue
penetrates water farther than red).
This is true mostly for salt water types of vegetation, especially algaes
and what-not.
Photo response for *fresh* water comes closer to terrestrial-type plants, in
that the depths involved and absorption of the red end of the spectrum is
minimized due to the limited depths and types of water involved. You have to
look *very* hard to find fresh water plants outside of plankton and algaes
that grow at the depths most people think of when picturing a salt water
environment. Most of the plants we grow in non-salt aquaria come from bogs,
marshes, swamps, flooded forest floors and streams which consist of bodies
of water whose vast majority range from a couple of inches to about 60 or so
feet deep. Most reef systems seem to start at about 30 - 60 feet, and
deeper.
Terrestrial plants have a maximized photo*tropic* response at around 440 nm,
meaning that their response is to grow toward and/or face the sunlight in
order to expose the maximum amount of surface area for photsynthesis. There
is a good bit of photosynthetic activity in this range, but is usually
limited to about 50% of potential.
Maximized photosynthetic response occurs across a double peak, with about a
90% response at just around 610 nm, dipping below that slightly past 610 to
rise back up to full potential in the 620 nm range.
Because there is both phototropic and photosynthetic response across the
spectrum, despite maximized responses at separate ends, intensity is more
critical than spectrum. A plant will grow no matter what the spectrum if the
light is intense enough. If there isn't enough light, well...
Human eyes seem to have the sway in placing importance on spectrum. Since
most types of commonly available lamps concentrate in the 500's and give
acceptable responses, color rendition toward either the red or blue end with
specialized lamps is more personal a consideration. After all, no one can
tell *us* when *our* fish look their best as well as *we* can.
-Y-
nest...@mindspring.chkr.com
"chkr." is for mail-bots
patrick timlin
Eric wrote:
: it's the CRI that you pay for when considering the differences between
: a Chroma-50 (75 CRI?) and a VitaLite (95+ CRI?). The sun has a CRI of
Eric, just for your info, Chroma 50 lamps have a CRI of 90 and a coloer
temp of 5000 Kelvin.
Patrick Timlin http://www.geocities.com/CapeCanaveral/4742/
pti...@geocities.com