Robert brings up an important point that I should have mentioned before. The pH swings in an aquarium that one should worry about have to do with changing levels of total dissolved solids. pH fluctuations from CO2 addition have little to no effect on fish. If the fish are ever gasping it is because the CO2 levels are too high, not too acidic.RTRJR wrote:I don't think the tank effect on pH is very meaningful to the fish under any circumstances - they don't read it anyway.