Loctite 592 PST.
Tape SHOULDNT be used, especially on any of the pressure or supply lines...
HOWEVER, lately ive been seeing major issues with chinese sched 40 pipe and fittings being basically crap, and leaking like a sieve no matter what dope was used or tightness achieved.
A trick i learned from an old timer was to smear dope on the threads first, then a wrap or 2 of tape 2-4 threads back from the opening (so you dont contaminate the fluid), then cover that with a layer of dope. You WONT have any leaks after this, even on poorly made fittings. But you muat take extreme care to keep the tape well back from the opening, especially on supply lines to the pump.
Another oldtimers trick was to wrap the threads of the pipe in silk thread along with dope. I havent done the latter, but have had great luck with the above trick on problematic fittings.