I am running a pressurized CO2 system and need a good reliable check valve. Can someone point me in the right direction. I want one I can count on not the cheapo plastic one from the pet store. Thanks

These are pricey, but have worked for me.

CO2 Brass Check Valve - AquaCave

I believe this is Orlando's site

Aquarium Check Valve | Inline Check Valve

And Rex's site

The Best Aquarium Regulator & CO2 Parts

I will try a clippard next time, price looks right. Sure these work fine.