Leak in fiberglass pool - can't find the reason

asura1

Well-known member
Jun 18, 2024
49
Barrie, ON
Pool Size
14000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Jandy Truclear / Ei
Hi all, I'm getting a little desperate here.

I have determined that my fibreglass pool leaks at the rate of about 1 inch a day. As it takes me about 3 hours to fill the pool just to maintain it at the same level every day, I'm estimating about 600 gal (2200 L) of water loss a day.

That level of loss is roughly the same with pump on or pump off, so it's probably somewhere in the pool itself.

The pool is aged (my guess is 30-40 years old) and there are some visible cracks in several places. I did the dye test myself, couldn't find anything. Got my pool guy to do it all around the pool, nothing.

He plugged off the skimmer and both returns, no change in water loss. Hydrostatic valve looked loose so he sealed off the main drain with pool putty, still the same.

He's thinking it could just be the pool showing its age and water is slowly permeating through the fibreglass surface, even though we could find no apparent leaks.

Next step according to him would be to drain the pool and replaster the surface. While I'm prepared to face this eventuality, I'm just not ready to do it just weeks after we moved in.

Does this make sense? Should I get a professional leak detection company to do a more thorough assessment?

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Rant that is irrelevant to this post: I love having a pool but it's just been a lot of issues so far and it's weighing down on me mentally, even after we resolve this one, I'm aware there are other things coming up (new heater?) I know it's only a matter of $$$ but it is a lot right now.

Rant over, apologies all.
 
Would it leak even with the pump off and all openings in the pool sealed though?
Good point. No it should not. But if the shell is intact, water has to be leaking from one of the penetration points. Did you notice exactly how the return jets were plugged? If a jet is cracked inside at the threads, it can still leak if not completely sealed. That happened to me. See the link below at post #32.

 
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Update: I had a leak detection company come examine the pool and they were able to electronically identify a noticeable (and very clearly audible even to naked ears, once the tech blew air through the pipes) leak behind the return, not the one in the deep end with a big hole behind the deck, but the one in the shallow end.

If a jet is cracked inside at the threads, it can still leak if not completely sealed

This was indeed quite plausible.

Another thing I have been somehow quite oblivious to, is that, my pool is actually a hybrid fiberglass wall/concrete floor 😳
 
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