[stcyrwm]

actually im just curious now, how come fluctations in Co2 production would cause algae??

like say Co2 fluctuated between 30 ppm and say 40 ppm, would that cause algae? or is it not the action of fluctuation that causes algae, but rather the fact that it dips below 30 ppm when it fluctuates?

My experience was that as long as the DIY CO2 was above 30ppm then the fluctuations didn't matter. The problem for me was that meant fluctuations up high enough to have the fish gasping at the surface which always freaked me out. I tried dealing with this with airstones on timers but it just all made me too nervous so I backed lighting down to 2wpg and dropped the CO2 altogether. This has actually worked remarkably well for me with a lot of plants I thought I couldn't grow this way.

Tom's thread "CO2 Revelations" also opens the possibility of not having to have 30 ppm but instead focusing on diffusion to give you lots of microbubbles of 100% CO2 in direct contact with leaves. This might possibly solve the problem with DIY CO2........