Yes, I just did as a matter of fact. I am getting nothing coming out of the clippard brass check valve. I put a Lee check valve and that worked, so I hooked the tubing up to my reactor and the water flowing through the reactor ended up flowing back to the check valve. It seems that the water pressure in the reactor is stronger than the CO2 pressure. I waited some time to see if the CO2 would push through into the reactor, but I got nothing. I checked all my CO2 seals with a water and soap solution and I do not see any leaks. I had my dad check it for another pair of eyes and it seemed fine to him. So, I sit here watching my Eheim powerhead with the CO2 tubing attached and it seems to be working. It has been 2 days now and my 2 drop checkers are changing from blue to green and my PH goes from 7.2 before lights and CO2 kick on at 8am to currently 6.8 at 2pm. If this works I am sticking with this system.