hoppycalif· Premium Member
You have to use a needle valve. Without a needle valve you are forcing far too much CO2 into the reactor, and your CO2 tank will be empty in a few hours. The CO2 flow rate needed for an aquarium is extremely small, so small that it takes a pretty good needle valve to allow an adjustment down to such a small flow. The person who said you don't need a needle valve was mistaken.