Where would you introduce CO2? Thanks!
Some how, somewhere between the bio-balls and the pump.
I realize there isn't much room there. But the bio needs oxygen, so it really needs to be after that.
Where would you introduce CO2? Thanks!

how are you going to filter the tank then? no point in bio balls if your going to turn off the filter all the time.
now sure how well the bacteria will stay alive in the filter with the motor off 10 hours a day.