The pneumatic check valve can prevent the aquarium from flowing back water. which is caused by the decrease. and maintain the function and life of the carbon dioxide cylinder. NOTICE: Used for carbon dioxide steel pressure vessels only and cannot be used for DIY and oxygen pumps because the pressure does not 39; is not sufficient to operate the valves.When used in the ozone generator. the air check valve can prevent ozone from flowing back to the air pump and chafing the propeller.The air check valve The aquarium can protect the feed head from water backflow caused by power outage.Simple check valve is easy to install. requires no additional tools and can be attached to any desired location in seconds.These one-way stainless steel check valves are suitable for the CO2 supply system in aquariums. aquarium and others.