One co2 dump, and loads of fish die off will quickly show you how valuable a pH monitor/controller is.cassharper;2200860;2200860 said:just hook a timer (any cheap lamp timer at wall mart will work) up to a solenoid valve to turn the CO2 off with the lights.
If you want to get super pretentious you can also add a pH monitor to a solenoid valve. In theory when CO2 builds up it will have dissolved carbonic acid in the water thus lowering the pH... that's when your monitor shuts off the CO2. Waste of $200 IMO, but some seem to like it.