i got a used fluval 204. I was running it and after a while i noticed a small leak, so i took it apart. the seal looks good and i didn't notice any cracks but i didn't look very hard. So i put it back together and vasolined the seal and hooked it back up and ran it for about an hour and in about 1 hour it leaked about 2 inches of water out of my 90g (not the only type of filter). so i took it and now it sits. can you help me with the leaking problem.