[flyyyguy]

I very seldom use teflon tape for threaded PVC or for threaded pump connections. Silicone or pipe dope is much better.

I generally use silicone. Just a smallish bead around the top inside lip of the female part and thread in where comfortable and it will seal perfectly every time. Its removable, will never leak and especially for threading tapered fittings into bulkheads, or more importantly pump volutes, when using silicone you do not need to thread the fitting in all that far to make a perfect seal so your tapered fitting wont potentially stress and break the volute.