OK, you're trying to jury rig this until you can replace the tank, so creative responses that are not exactly the professional way of doing things are allowed. Let me give you a procedural clue that seems to escape some mechanics, often on automotive engines. Get a good quality sealant
, such as DuPont 5200. Coat the outside of the nipple, not the inside of the hose, and ease it into place, leaving the clamps loose. Do not tighten the clamps until the sealant
has set. Then tighten the clamps. People tend to put on the goo and tighten the clamps immediately. That prevents to goo from making a pressure seal, because it just oozes out wherever the clamp tightens. You end up with just the strength of the hardened goo for your seal, when what you need is to create a hard rubbery gasket
and then, and only then, tighten down on it with the clamp. Good luck with it. If you don't have access to 5200 or comparable, buy the silicone sealant with the largest number of years of claimed life - that's a measure of how little water
it has in it, and as a result, how little it will shrink when dry.