I have a 55 gallon planted tank with a 300 gph biowheel and a 300 gph
aquaclear.
I just started a DIY CO2 injection system (yeast and sugar water in a 2
liter soda plastic soda bottle; I run the airline into the intake to the
Aquaclear filter, where the impeller chops it up).
This bubbles every 5-7 seconds or so, adding CO2 to the tank around the
clock.
I understand how the flow would tend to stir the CO2 out of the mix, but
it seems to me that, with the steady flow of CO2 bubbles, a greater
concentration of the gas is present than would otherwise be the case is
present, though I haven't measured it.
BTW, my substrate is gravel over vermiculite, and is unheated. I add Kent
plant food weekly.
This is my first planted tank, and so far so good! My M. praecox really
look good in the plants when the sun shines in every morning.
-- Stephen
stephenbou at aol.com
http://members.aol.com/stephenbou/cichlids.html