Re: NANFA-- CO2? - Fill your planted tanks with mudminnows or anabantids!

Bruce Stallsmith (
Fri, 19 Jan 2001 16:55:51 -0500

Mark, you brought up a point most people don't consider about CO2 as a
"fuel" molecule for aquatic photosynthesizers--there's evidence that some
(many?) aquatic systems can use bicarbonate ions, HCO3-, as an initial
source for photosynthesis. Peak demand for CO2 in an aquatic system can
remove CO2 from the water, say in early afternoon on a hot day with bright
sunshine; _everything_ green is sucking in CO2 as fast as they can find it,
and CO2 is not especially water soluble. So, use the next best
thing--bicarbonate ions, which will be relatively common in water as it
becomes more basic from losing dissolved CO2 (source of carbonic acid). My
understanding is that the bicarbonate can be enzymatically changed to CO2
inside the cell.

So, maybe don't follow fashion and fight a losing battle to hypersaturate
your waters with CO2, but develop a steady source in your tank for
bicarbonate ions (which are much more water soluble than CO2).

Just a thought...

--Bruce Stallsmith
Huntsville, AL

>Speaking from complete ignorance, I would make two observations -- First, I
>would expect that CO2 as a carbon source would be irreplaceable. Any plant
>physiologists out there? If these additives can produce dissolved CO2 in
>the water, then that's all you need, right? I guess another possible
>carbon source would be that which is used in tissue culture, where
>carbohydrates are fed to the plants directly. This has to be done in
>sterile conditions so that the carbohydrates are not consumed by
>microorganisms. Still, you don't get normal plant growth without
>photosynthesis, which as far as I know, requires CO2 (carbon dioxide gas).
>Second, my suggestion for adding CO2 would be by adding fish or other
>respiring aquatic creatures. Perhaps air breathing fishes would be
>preferable, since they don't require high oxygenation and, as far as I
>know, release CO2 via their gills, directly into the water. Anyone know
>whether air breathing fishes use the atmosphere to release CO2? Hmm, never
>thought about that! So, here's a new idea (as far as I know) -- fill your
>planted tanks with mudminnows or anabantids!
>Need budminnows? Visit...
>Columbus Ohio USA <))><

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