The CO2 needle valve usually sits at the end of the CO2 regulator. The needle valve allows fine adjustment of CO2 delivery. Needle valves can get clogged so they need to be replaced occasionally. A CO2 pinch valve also allows control of CO2 delivery, but without the same level of precision. Every aquarium CO2 system should have a CO2 check valve. The check valve prevents water from damaging the CO2 regulator by flowing up the CO2 tubing. A CO2 brass check valve is a quality option. If you have any questions about CO2 gas bottle fittings for your aquarium setup, contact our expert support.
Ultum Nature SystemsCO2 Paintball Adapter (CGA-320) - Ultum Nature Systems