Leaking end cap

[Minnesota Tapper]

I ran water into my r.o. for the first time to get The membranes wet. I just ran the booster pump to do this. I accidentally had my needle valve almost closed so I had 50 psi in the canister. Meanwhile I'm checking lines for leaks etc. Wasnt Any issue until I shut the pump off. After the psi went to zero water started running out the bottom end cap. Where the end cap meets the s.s. tube (under the clamp). So I did it again, didnt leak under pressure but leaked when no pressure. I had to got to work so I didnt look into it but in at a loss as to how that's even possible. What should I be looking fir when i take it apart? It's a fast leak. It drained the membrane canister in a couple minutes.
I have end caps from fresh water systems, mes membrane. Thanks for ANY info!

[Bricklayer]

One or both of your orings might of rolled over and came out of the groove when you put the end cap on. Did you put food grade grease on the orings. I usually put some on the inside of the canister as well. About 2 “ down. Your end cap might not be in all the way. It should be tight against the stainless lip.
Clamp not tight enough maybe also. The two sides of the clamps where the bolts are should almost be touching after you tighten the bolts.
Could it be the fittings leaking instead of the canister. ? Check them as well.

[Minnesota Tapper]

I used grease and was really careful installing. My clamp halves are not quite almost touching. Maybe I can tighten them some more. I was worried id over tighten them and distort something. Sounds like really tight is good.