I got a 55g water tank (Ace Roto: https://www.ruralking.com/ace-roto-mold-55-gallon-vertical-dome-top-vt0055-20.html) to hold RO/DI water. It came with a bulkhead with a threaded Female NPT. I went to Home Depot and got a male NPT to slip converter, and put on a spare union ballhead that I had laying around. Unfortunately, I have a super slow leak from the threads between bulkhead and the MPT > Slip fitting. It drips probably once every 10 minutes or so. I actually stood there for 10 minutes and didn't see much happen, but I think a new drop of water came off of it, who knows. There's a constant wet spot and I can see a small bit of water collect on the plumbing. I threaded it as far in as I could. I tried using some plumbers tape, but that didn't work either. Any ideas? Things I'm thinking of trying 1. Use plumber cement (is this safe?) 2. Use silicon on the threads and rethread it in 3. Replacing the bulkhead with a slip bulkhead instead of threaded (somehow, not sure how I can get my hand all the way into this tank to put it together) Any other ideas?