Maximum saturation of CO2 in water is not an easy number to calculate since it is dependent on so many variables (pH, pressure, temperature, other solutes, etc.).
Aaron, I hope that you don't mind if I annex the thread a bit here. :mrgreen: Edward, how can you sustain 300 ppm CO2 when your tank is virtually devoid of carbonates? Moreover, how can it not exhibit a pH-crash? Even if a pH-crash is not possible, does the fauna not die from too much CO2 even if there's plenty of O2 around? I am thinking 300 ppm CO2 is enough to affect the diffusion of CO2 out of a fish's body. Or is 300 just sound big to me?
I've always been told that CO3 is vital to protect the pH from changing too drastically, thus killing the fauna. If this is not true (and I would like to know why, if possible), then it would save me a lot of trouble. I currently dose CaCO3 as a source of both Ca and CO3. I wouldn't mind switching to CaCl2 since it doesn't cloud the water for several hours like CaCO3 does.
Thanks much.