Just discovered that the return jet fixture is leaking. The leak seems to be on the inside of the pool, water's coming out around the fitting. Previous owner used some kind of putty around it on the outside (thread side but not on the threads themselves) but that's all crumbled and nasty looking.
So, I'm figuring sealing it from the pool side, what would be better, a flat gasket so it covers more area or just an O-ring (assuming I can find the right size).
Or just use plumbers dope like the previous folks did?