I’ve never used any type of sealant before and I have a half dozen hoses set up.
But… I do have one set of plugs that are fairly new that are giving me a hard time sealing up. All of these I put together in the past I just used a large screwdriver and tightened the hose clamps by hand, let the set awhile, then tightened again. No problem…..
this last one I used my impact cordless drill with a hex head bit and ruined two of the hose clamps…. Bad choice… got em too tight and stripped out the hose clamp.
If you were to use some type of gasket sealer, I would use something that does not get hard, and could be removed in the future.
You can test these right in your form by using a small cup of water with dish soap mixed in, and a small paint brush…. Any small leaks will make bubbles. You test natural gas piping or propane lines the same way.