Leak City USA, population Me.

[endeitz]

Background:

1. Central TX, 4 yo inground gunite pool, about 15,000 gal, DE filter, chlorine tabs
2. 4 "normal" returns
3. 1 "fountain" (basically a return) on the beach entry step
4. 1 "waterfall" feature on the backside
5. Basic polaris with a booster pump

We do not drain our pool in the winter, as freezing temperatures rarely last even 24 hours. However, this winter the pool started leaking. We are currently losing about 4" overnight without the pump running.

Troubleshoot #1: I shut everything down and let it leak until it got to the lowest return "eyeball", and the decrease in water level stopped there. The pool light is beneath the returns in elevation, so I am thinking the leak is somewhere in the return line(s).

Troubleshoot #2: I bought 5 threaded plugs for the "normal" returns and the "fountain". Unscrewed all the eyeballs (with some difficulty) and put in the plugs. The leak continued unabated.

Troubleshoot #3: Refilled pool, removed one of the threaded plugs. Can feel an actual pull from the return (i.e. the plug is "sucked" into the return). Verified with food coloring, water is flowing into any of the 4 normal returns if I remove the plug. Looking at the plumbing, I think the cleaner is plumbed into the return lines (probably this is common knowledge, but I am learning here), hence the continued leakage when I plug the returns. See picture below.



So there is a leak in the return lines, somewhere. I am losing significant water, but cannot detect any wet spot in the yard between the pool and the equipment shed. I suspect it's under the limestone deck, which will be costly to dig up.

I purchased some "fix-a-leak":

https://www.amazon.com/Fix-Leak-Pool-Sealer-32/dp/B003K1E99Y

I have read the instructions, but my thought is that I would like to isolate the leaking portion of the plumbing as best I can, and just put the "fix-a-leak" in that portion. What I am wondering is if the flow to the leak is strong enough to bring the "fix-a-leak" compound to the problem. It seems like a pretty viscous material, so although I can feel the "suck" at a single return (when the other returns are plugged), I don't know if sufficient flow is occurring to drag the leak compound to the problem area. I am looking to find an advantage of some kind, so here are my questions:

1. What is the "high side" on pool return plumbing, where I could put in the leak compound and at least get some gravity assist to move it through the system?
2. Could I plug all of the returns, and then turn on the main pump, adjusting the valve to run a fraction of the normal flow through the return line, forcing some water through the leak? Then add the leak compound on the front side of the return lines (through the chlorinator for instance) to move the leak compound directly to the problem area?
3. Am I nuts, do these kinds of leak compounds require a high velocity to move them through the plumbing?

I am on a learning curve here, and have probably not provided enough relevant information. I appreciate any feedback folks could provide.

Thanks,

Ed.

 

[duraleigh]

Hey, Ed,.

I have never known fix-a-leak to work well.

Is all of your visible plumbing higher than the pool water level?

Everyone likes to think underground plumbing is the culprit but it rarely is.

Is any of your decking cracked?

 

[endeitz]

Hi duraleigh, I appreciate the help.

My visible plumbing is in a pump shed about 40 feet from the pool. Topography is sloping downward toward the shed, and the pool was built up a bit (to keep overland flow from hard rains off the deck), so I suspect that none of the visible plumbing is above the pool water level. I have looked pretty closely at the plumbing and ground beneath in the pump shed for signs of leaking. Because we are losing something like 750-1000 gallons overnight, I think it would be visible in any of the soft dirt of the pump shed floor. The pool and trenching was excavated through clay and limestone, and we have a pretty shallow limestone aquifer beneath (our water well is in that aquifer). My initial suspicion was that the leak is under the decking and is going straight through the fractured limestone to the water table beneath, but I can't know for sure.

I like you idea of the leak being in the aboveground plumbing, so I will do a more thorough inspection when I get home tonight, and do some probing in the dirt to make sure I'm not missing something.

Bummer about fix-a-leak. I will probably try it since I spent the $20 already.

Thanks,

Ed.

 

[duraleigh]

Assuming you have a multiport valve, put it in the closed position. This should isolate the pool and return lines from the rest of the system.

If it doesn't leak, the leak is not in the returns. If it does still leak, it is LIKELY in the return lines but could be hiding somewhere in the pool body.