Hi! I have what I initially thought was a very SIMPLE problem, but... Here's the situation: I have a tiny leak but it's in a pipe that does NOT carry water under pressure. It's in my hot-water HEATING system, and I have the old-fashioned kind of hot-water system-- without a pump to circulate the water-- so the only force promoting the leak is gravity, i.e. the weight of the water above the leak, which is in a vertical pipe near the boiler. At the moment, the leak is just a very slow drip (less than one drop a minute) though when I fully refill the system and the weight of the water above the leak is heavier, it will be faster, but still slow. So, I originally posted my question about how to stop this leak on a general do-it-yourself site, where the responder linked me to a page with a variety of pipe thread sealants: pastes, tapes, sprays. He said I could use any of those products to seal the tiny leak. So I went to Home Depot and got a small tube of Hercules Megaloc Multi-purpose Thread Sealant, which is a non-hardening paste. But when I read the instructions, it seemed the product was only intended to be used by spreading it on the thread BEFORE joining two pipes, not putting it on the outside of an already-dripping pipe. So I called the manufacturer's customer service dept. and spoke to someone there who confirmed my doubts-- he said it absolutely was not designed for the purpose I wanted to put it to. Luckily, when I was at Home Depot I already was uncertain about the Megaloc Sealant's appropriateness, so I also bought an epoxy that could be used in a watery environment, J-B Weld Water Weld-- later, I called that company and spoke to a customer service rep who said that their product could indeed stop the drip, as long as I roughened the surface of the pipe so that the epoxy would adhere properly. Then I was thinking that maybe the best idea would be to use BOTH products-- spread the Megaloc Thread Sealant around the entire circumference of the leaking joint (stuffing it in between the outer pipe and the inner pipe) and then apply the J-B Weld Water Weld epoxy over the whole area. What do you guys think of that-- would the Thread Sealant interfere with the epoxy? Or is the thread sealant unnecessary and would I do just as well only applying the epoxy? And maybe everything I said above is going down the wrong track-- maybe both the sealant and the epoxy (whether used alone or with the sealant) are bad ideas-- and there's some better plan I could implement. If so, please let me know about it!! I'm a novice in need of sound advice!