+1 on the fan.
CO2 does not force you to increase light if we're talking about plant growth. It's the other way around. Also, from the fish's perspective, the O2 produced by the plants will not keep them from dying if you go over board.
Sorry I think I'm not getting what your saying.
If I used less Co2 I would have to cut the light because I would be Co2 deficient.
I believe I have (up until the air stone) a severe o2 deficiency.
(due to glass and canopy)