Type of bulkhead (wet side + dry side) - threaded + threaded; threaded + slip or slip

[byee]

I wrapped 3 layers of Teflon tape onto the 3/4" return and hand tightened into the bulkhead based on the threads in comparison to the 1" herbie drains which I was able to easily hand tighten all the way.

Perhaps I need to try other 3/4" MPT's.

I decided to test anyways by re-installing the 3/4" return into my cube. Needless to say......it's got a slow leak

Any suggestions?? I've tried 2 bulkheads and 2 different brands of 3/4" MPT's......gets very tight after a few turns into the bulkhead even with the use of Teflon tape.