Originally Posted by stinkyattic
All regulators I've ever seen have glass-fronted dials, but there is a second part that has a ball in it. You really want a regulator that has that built-in solenoid valve. You can use your existing tank, but you need the solenoid to be able to run the system on a timer correctly. Constant seep is POSSIBLE, but not practical or efficient, since you only need it in light time, and will probably end up seeping too much gas too fast- not good.
Remember for CO2 to even matter, you need intense light, perfect conditions, and a good fertilizer regime.