If I increase the CO2 any higher, it starts killing my fish. One thing though is the levels don't get high enough to cause this until about 6-7 hours into injection (I start co2 1.5 hours before lights on). My dropchecker turns yellow at around 5-6 hours into injection. My HC begins to pearl around 2 hours before the lights go out at the end of the day. This doesn't seem optimal to me.
Could this be a circulation problem? The bubble rate is constant and can not be increased due to the overdose issue, and seems to be diffusing ok, but at a very slow rate.
I have a 2217 with inflow and outflow both on one side of the tank. I can see the water make a full loop of the top of the tank via the floaters, but I can see there may be some dead spots closer to the surface. I'd rather not throw in an ugly/noisy powerhead but I will if I need to!
The other issue is light. I have 10 cree XT-E's running at 350ma around 1.5 feet above the tank. Too much light, too little? They can be adjusted up to 700ma if desired.