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Re: CO2 or not CO2

On Sun, 13 Dec 1998, James Purchase wrote:


> I want to see if there are any qualatative differences between the major
> lines of aquarium fertilizers/substrates. If adding CO2 can be so
> problematic (insofar as ensuring equality among 4 separate tanks), perhaps I
> should just forego the use of supplemental CO2 altogether. That way, any
> differences in the tank would be more than likely due to the completeness of
> the fertilizers than it would be to more or less CO2 (and we all know how
> well CO2 can enhance growth).
> If I omit fish from the tanks during the period of the study I could cut out
> yet another variable.

If you don't add CO2 and omit fish then I think your tanks will all need
to be the same size, with the same circulation.  The atmosphere is your
only CO2 supply and you have to make sure that the tanks all get the same
atmospheric exposure.

Without fish in the tanks (leaving fish out is a good thing for keeping
conditions controlled) you will need to provide all nutrients via
fertilizers.  Most of us depend rather heavily on fish food as a source of
nutrients.  Also, without fish and fish food the background respiration
that most of us have in our tanks will be gone.  That respiration is a
source of CO2.  With the background respiration the CO2 levels are
probably 3-4 mg/l on a regular basis; without it you might not see CO2
levels over 0.5 mg/l.

Roger Miller