Hi, I have a 180l SA setup which I've ordered a pressurised CO2 kit for. I run the tank at 32 degress C, which of course lowers dissolved O2, therefore I run air into the tank via the outlet of the powerhead. This causes a lot of surface agitation. I experimented with turning of the air pump yesyerday and woke this morning to find all the fish hanging at the surface. Immediately I put the air pump back on and the difference was instant. So, how do I run an air pump into the tank as well as CO2 injection without gassing off too much of my CO2?