addicted2reefin

a good pressure relief valve that i did back in the day and cost about 20 cents. If you can find a small ballon, put it on a T, and as pressure builds up the balloon pops off, simmiliar to the syringe.

ncutler

I've since added a 950 ml bottle to the 3 way valve. It functions as a resevoir that increases the total amount of co2 the system can store. I've not had to worry about too much pressure, I've checked daily and it appears as long as co2 is being let into the aquarium, it doesn't build up to dangerous levels (I can always depress the bottle a bit).

I've also noticed that the side benefit of having a resevoir means that using the type of check valves I use (spring loaded), as soon as I undo one bottle, the back pressure closes the check valve tightly, allowing me to change a bottle without it stopping the flow.