[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

CO2 injection myth (was Re: Algae in goldfish tank)

Olga wrote:

>Jessica wrote:
>>.... I am attempting a CO2 DIY
>>thing, but it isn't very successful, I'm going to check for leaks this
>I'm not sure how beneficial this will be with only a little over one watt
>per gallon of light. Also remember that the goldies need LOTS of oxygen and
>this will cut their oxygen at night.

Careful here.  Under normal conditions, dissolving CO2 into the tank will not
drive out oxygen any more than dissolving salt into the water does.  Think of 
it in terms of partial pressures.  The oxygen will come to an equilibrium 
dictated by the effective partial pressure of oxygen in the air, the consumption
of the oxygen in the water, the generation of oxygen by photosynthesis, and the 
dissolving rate at the surface.  The CO2 has its own equilibrium, enhanced by 
the CO2 injection.

What you might have to worry about at night is the drop in pH due to lack of
consumption of CO2 (new equilibrium).  Even then, I have to agree with George
Booth and a few others in that I'd be more worried about *bigger* pH swings 
when the CO2 production stops and starts with the lights.  I believe George
might have some experimental data showing bigger pH swings when the CO2
production is turned off with the lights.