Review on Aquarium CO2 Regulator with 12V DC Solenoid - Large Dual Gauge Display, Bubble Counter, Check Valve - Fits Standard US Tanks - Accurate and Easily Adjustable Flow Meter by Adam Noorzay

I like it so far. This is great because it only has one adjustment knob. The set operating pressure is now set. I hooked it up to a paintball tank with an adapter and it works great. The only thing I don't like is how noisy the solenoid is when it's turned on or off. This only happens twice a day so it's not a big deal, but it can be scary when you're around. The adjustment is a bit fiddly, it took me a while to get it where I need it. After that it doesn't need to be touched anymore, so everything is fine now.