Co2 not coming out of diffuser
New to co2. 10lb co2 tank, dual regulator, ceramic diffuser, co2 tubing. 33g long aquarium.
Initially when I was setting up the co2, I couldn’t get the diffuser to put anything out. Bubble counter was working fine. I put a new check valve on and that seemed to fix it (cause or correlation idk). For the last week everything was perfect.
Yesterday I decided to rescape everything and place the diffuser at the other end of the tank. I took off the air line and installed a new, longer one. Same check valve and same diffuser. Put it in the tank and nothing. I’ve since replaced lines, check valve, and even bought a new diffuser.
If I remove the diffuser and put the line in the water, the bubbles will start coming out of the line. If I put the diffuser back on, nothing. I can crank the gas up like mad and it will start to come out, but if I turn it back down to 1-2 bubbles then it will stop and I can actually see it reverse up the tube slowly.
Bad check valves? Line leaking?
Thanks for the help.