Longhorn forget the DIY Co2, get the Real McCoy. Ya can't beat Pressurised Co2, Ultimate control, BPM an all that. I'm doing 80 bpm, when I do a trim of the plants I pull it back to 60bpm for a couple of days (2 or3 days), then bump it back up again. The trouble with Half measures is ya get Half results. With a proper Co2 set up you can turn it off at night, plants don't use it at night. Mines on a timer along with my lights, Comes on and off with the front pair of lights, 15 minutes later my second pair come on.
Regards John.