Bulkhead Fittings...


New member
I bought 3 1" bulkhead fittings and every one of them have leaked. The first one leaked and then failed catastrophically while tightening it (to try and stop the leak); my 150g nearly emptied into the room because of the failure.

The second and third bulkehads (mounted behind overflows) leaked when tested.

I'm referring to threaded bulkheads; and the part of it that was leaking was the PVC threaded coupling ; not the flange seal (which was properly installed with the flange on the inside of the tank and gasket beneath the flange).

I ended up buying glue in fittings from an LFS

David_Winther said:
Probably a dumb question, but did you use any Teflon Tape when you put these together?


Well; a brochure that came with a used sump I bought was for a "hayward" bulkhead fitting; and it says tighten only hand tight plus 1/2 to 3/4 turns. Unfortunately the fittings that came from Marine Depot say nothing about how to tighten them; so I had just assumed to tighten with a wrench. At this point; I have little trust for a threaded bulkhead fitting when used in a pressure application; from now on I will use glued fittings for overflows and closed loops.

Hmmm, I use threaded bulkheads for everything in my tank. Haven't had any problems yet. A big time/pain saver if you ever had to open your line for some reason. That glue doesn't want to come apart! ;)

Not saying you did anything wrong, but something is definately wrong. I have at least six on my tank alone and have seen a lot more in use on different tanks. And I have never seen one leak. Its a little odd you would end up with that many faulty ones. You really can not tighten them with any wrench or you will over tighten them.
Hence, the problem; I had initially tightened them with a wrench thinking that you just turn them down like any other threaded PVC fitting. The product said absolutely nothing about just hand tightening them; so I had no way of knowing how much to tighten them.

If you hand tighten the fitting and then it leaks; what are you supposed to do? The situation is ambiguous. I just replaced the fittings with slip fittings and glued in flex PVC. If I ever need to take out the fitting I will just cut the piece of flex-PVC off (leaving extra length on the fitting side). That way, the fitting can be re-used.

I mentioned this without knowing what I had done wrong; thanks for confirming what the problem was.

This is definitely an honest to god mistake as I have done exactly that not with this particular bulkhead but with lot of different plumbing fittings back 15 or so years ago. Needless to say, I ended up with leaks right away on a few fittings, and a few cracked ones some years down the line. I'm still a big fan on using threaded fittings as it allows me more flexible reconfiguration. Still, I silicone everything to be safe, and I keep a very close eye those first few days when doing a test run on the plumbing with a system full of a test batch of freshwater. After that, I still check the joint quality every so often. This pretty goes for everything I do with the tank. It never hurts to be too safe. Nowadays, I call Spears, Dura, or any other fittings manufacturer before I do something I never did before.

I don't understand the reasoning behind buying a fitting that is threaded and then having to glue it together to get it to seal. I understand that "it works" that the non-seal of a threaded bulkhead is common, etc.; but it points to the fact that a plastic bulkhead fitting should be a glued joint rather than a threaded one. If you glue the threads with silicone; then you need to clean it up to re-use them and get a good seal the next time around (not worth it to me). If you're careful and use plenty of glue for the slip fittings you should never have a problem with it leaking becasue it self-seals; less worry about the fitting cracking after time either.