question about biological filtration
Richard Sexton
In article <1...@bacchus.DEC.COM> re...@decwrl.UUCP (Brian Reid) writes:
>
>I am puzzled why it is not possible to set up outboard gravel filters. It
>seems to me that as long as the water flows through bacteria colonies in the
>gravel, it shouldn't matter whether the gravel is at the bottom of the tank
>or off in another room. Why couldn't you have a circulating pump that drew
>water out of the marine tank, pumped it through a large bank of gravel beds
>that was kept nearby, and then pumped it back into the aquarium?
Quite doable. I remeber a British aquarium book, about 20 years old
that showed how to make an 'algae' filter. You piped water out of the
tank into a shallow tank, with the same width and bredth as the original
tank. It was to contain pea sized gravel, and had strong lights over it.
As they say (and say and say and say) in soc.singles: go for it.
>Maybe I'm weird, but I've never liked the appearance of gravel beds. My
>freshwater aquarium doesn't have any gravel at all, and it has done just fine
>for years. With no gravel in the tank there is no danger of anaerobic pockets
>forming under it, and cleaning the bottom is a snap. There is a nice colony
>of bacteria in a sponge in the power filter.
Not wierd at all. Gravel has its place. I have one tank that has a 3 - 4"
layer of gravel, lots of plants, and is essentially a decorative tank.
My other tanks are for raising fish, and get lots of food, and have the water
changed more frequently. They have no gravel for the reasons you describe
above. The plants are in clay flowerpots. "no worries".
>Brian Reid
--
Its too dark to put my keys in Santa Fe, or something like that.
ric...@gryphon.CTS.COM
Patti Beadles
>
>I am puzzled why it is not possible to set up outboard gravel filters.
It is. The idea is that you have to filter the water through whatever it
is you're using. This material develops a colony of nitrifying bacteria on
the exposed surfaces, and helps keep the nasty stuff out of your aquarium.
If you've been following the "Dutch Minireef" information in FAMA, you can
see that one of the main principles is an external biological filter with
large surface area.
>Perhaps the answer is that there are other substances that are more efficient
>than gravel when used outboard, such as polyester floss. Perhaps these
>"Bio-balls" things, that I read about but don't quite comprehend, are a
>gravel substitute for forming bacteria colonies on outboard filters.
Bio-balls are small (1" diameter) balls that have "prongs" all over them.
Thus, they have a very large surface area for their volume. By putting them
in an external trickle filter (where water drips over them instead of having
them completely submerged) you get a high capacity for organic waste breakdown,
and a high dissolved oxygen content. Youu can also use them in an external
canister filter.
>Brian Reid
--
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