With anything that has a rubber seal to keep salt water in or out I have put a little smear of vaseline and it has allways seemed to do the job but can anyone tell me if I should do the same on a bulkhead on my 10mm thickness glass tank.
There isn't a need for that. Just make sure the glass is clean, gasket is on the flange side, go hand tight, then another 1/2 turn or so with a wrench.
