I've been trying to solve a leaky coupling on my hot tub's pump. The leaky coupling is above the pump (whereas the other connection on the pump runs to the heater, and is on the side of the pump). The other end of the leaking coupling goes to the filter (which is a pressurized filter container). The coupling has gradually been dripping more and more. I did a little research online, and most spa web sites recommend only to tighten these couplings hand tight, so I didn't want to over-do it and create a bigger problem.

I unscrewed the coupling, and saw there was a silicone-looking washer, but there did not appear to be any kind of washer or o-ring on the underside of the coupling.

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Based on a recommendation from a local pool & spa supply store, who said their pool guys use liquid Teflon-based thread sealant, I picked up some "Rectorseal T plus 2". I cleaned off most of the old (caulk-like?) sealant from the thread, then gooped on some Teflon sealant, tightened everything up, filled the tub, and plugged it in. I was dismayed to discover the coupling was leaking worse than before I messed with it!

What did I do wrong? Any suggestions for fixing this leaky coupling? Do I need to replace the washer and/or coupling? Add an o-ring inside the coupling?

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  • Replace the silicon washer. The pool store you mention should have it. With a good ring, you shouldn’t need anything on the threads
    – Tyson
    Commented Feb 26, 2018 at 16:05
  • @Tyson I think I'm going to try that--as you can maybe see from the picture, the silicone washer does not look to be in great shape--you can see one small nick on the edge of it in the included picture. Commented Feb 27, 2018 at 2:15

2 Answers 2


Your coupling or pipe might have a crack, too difficult for you to see or notice.

You are correct they are supposed to be hand tightened and that should be enough .

The connection on your coupling needs to be straight against your pipe this is where your seal should be. The coupling will not have a seal on the back side and should not - you state no-o-rings and that is correct.

Normally at the pipe to pipe connection is where your seal will be (You seem to indicate a silicone rubber seal). If the pipes are offset a bit - you can end up with a poor seal and the coupling will not perform. To exaggerate a bit think about a shim stick is wider at one end then the other - your connection of pipes might sit like that. In this case hand tighten will get so far and then will not function. You would need to wiggle your pipes into better position as you tighten to get rid of any offset. Given this coupling is by a pump and the way it is connected - the vibrations of the pump can cause some issues.

Your coupling might be worn at the threads and the fitting (or possibly a hair line crack).. might be better to simply replace it with a new one - I would replace it rather than play around with a $5 part - just faster, also I could ensure that my pipes were straight together perfect - so I have a nice fit.

Your liquid thread tape - if the pipes are fine threads use it and it might be ok, you will need to let it set up follow the directions.

I personally do not use it, I don't like it at all. I use the thread tape - I stretch the tape as I wrap and I roll backwards off of the tape core - wrapping my pipe. I make sure I stretched a little so it fits nicely in the threads of the pipe - in a coarse thread like that coupling I would have several wraps - the tape is cheap enough and I want a good fit and good seal - the coupling should go on a little snug to turn but not so difficult that it could break.

  • That sounds like it's the right advice, but as you can maybe see from the pic, the easiest way would be to hacksaw off the old coupling and put on one of those 2-piece screw-together repair couplings. Otherwise, I'm probably having to cut that short PVC pipe in half to get the coupling off, which leaves me with another repair to fix. So a $5 part, but a bit of effort to do it right in a small confined space inside my hot tub's access panel. Commented Feb 27, 2018 at 2:20
  • @OgrePsalm33 I understand it is difficult in a confined area - patience is a virtue but always cheaper to do it right the first time than it is the second time. Depending on how the pipe is connected at each end - maybe you can pull the thing out and re-work it ? I have used the tubing cutters for large size pipe - easier than hacksaw through the hole piece in a small space. Some ratchet styles will cut 2.5 inch or 3 inch - but I don't like them when the pipe is that large. Good Psalm of course they all are..
    – Ken
    Commented Feb 28, 2018 at 9:21
  • 1
    Circling back--finally got it all fixed. @Ken was right on the money about there being a crack too difficult to see or notice on the back side. I had a handy-man friend look at it, and he also said one of my gate valves had fallen closed (normally kept open), and it was causing back-pressure (which probably cracked the old coupling). Wound up replacing a whole assembly of flexible tubing, an elbow, a gate valve with new clip, and a pump union fitting. Runs great now with not a single drip! Commented Oct 1, 2018 at 2:04
  • @OgrePsalm33 Glad to hear you got it fixed. It really is one of those things that catches people off guard - because everything can 'seem' so perfect. I worked in a factory where we used a lot of pvc and sometimes you have to basically watch and wait for a slimmer of a blip of dew coming out; most of the chemicals would crust up and make it easier but water was the bear.
    – Ken
    Commented Oct 1, 2018 at 2:12

This is an O ring sealed fitting using any kind of pipe dope or Teflon tape will do nothing to seal the pipe. A new O ring is the only fix needed unless the fitting is cracked. Pull the O ring out and take it to a pool supply store or plumbing store and get a replacement. 1 small cut or notch in an O ring can cause a leak also after O rings have been compressed for a long time they deform and don't seal as well. O rings are cheap and this is probably the issue causing the leak.

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