|MadSci Network: Chemistry|
Tropical fish hobbyist add CO2 to the aquarium water in an attempt to enhance aquatic plant growth. The goal is a CO2 range of 15 to 20ppm. This range results in improved growth of aquatic plants while remaining safe for the fish. Aquarist attempt to determine the [CO2] using measured pH and carbonate hardness (KH). Rather than blindly accepting the formula given by fellow aquarist,([CO2]=3*KH*10^(7-pH), I would like to understand how it is derived. As of yet I have not received a clear explanation. I believe the starting point is the Henderson-Hassalbalch equation pH=pKa+log (proton acceptor/proton donor). The assumption is that carbonate is the only buffer system and temp 25C. Also some people feel that adding CO2 to low KH water can result in rapid/large pH swings, is this accurate?
Re: Determining CO2 in H2O soln using carbonate hardness and pH
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