You can use a drop checker to monitor co2 levels in your tank. If your regulator is equiped with a solenoid then you can just use a timer to turn on, and shut of your co2 supply. A ph controller is not really necessary. IMO. I have my lights, and co2 on separate timers. The co2 comes on about 1 hr. after the lights, and goes off about 1 hr. before the lights.