Leak detection and repair - suggestions?

[George in Georgia]

I've been struggling with water quality problems, and running the filter 24/7 for a couple weeks. The Forum has been invaluable in steering me in the right direction, and success seemed almost here.

But....

Friday I noted more of a drop in level than would be just evaporation, so I marked the pool level and set out a measuring cup filled to the one cup level. Saturday morning the pool was down by 3 inches, and below the skimmer inlet. Certainly not evaporation!

Since the liner is old - it has two tears above the water line, I suspected a liner leak. Since the water was still cloudy, I added some flocculant from Leslie's Saturday afternoon so that perhaps I could see a problem area. It calls for 2 hours of recirculation, then no filtration for 1 or 2 days. I also marked the water level when I shut off the pump.

This morning there was no perceptible drop in water level.

I suspect a leak in the pressure side, which naturally runs under the concrete pool surround, and comes up through the concrete slab in the poolhouse. Does anyone have any experience in dealing with this sort of problem? I know that radiator leaks can be fixed, at least temporarily, with various additives. I hesitate to replace the liner before this newest problem is fixed.

The pool is inground, about 25K gallons.
Sand filter, 1 hp pump.

Thanks for any advice.

[Poconos]

Sorry nobody has responded in a timely manner, myself included. Those radiator additives are for smaller, capillary type radiators and I wouldn't advise putting any of that stuff in a pool. It would probably be too diluted anyhow to do any plugging. Unfortunately I really have no advice and no experience fixing underground pipes. Only way I know is to dig them up. I'm told that some leak detection companies have a way of finding the exact place of a pipe break but don't know for sure. Plus I would think expensive. If there is any way to dig and expose part of the pipe you may luck out and find the break and fix it without having to jackhammer any concrete. Anyone else with ideas?
Al

[Spensar]

Before buying my house I had a pool service person check it out, which included pressuring the underground pipes only to check for leaks. He had a guage and ran a good test to verify if there were leaks there. That was several years ago and I can't recall the exact method, ie. did he plug the outlets, etc.

May be worth calling around and see if there is an experienced pro that can run such a test. I'm lucky to have access to a good one, that only does service and doesn't have a storefront so he isn't promoting "solutions" I don't need.

[waste]

Hi, welcome here!

Like Al, I'm sorry to have missed this til now

If the water loss is noticeably less with the pump off, it indicates a return side leak.

Is the entire area between the pool deck and the pump house concrete, or is there some yard involved?

Areas covered by crete can be checked (with ~ 50 - 50 chance of success) by using geophones (or Al's trick of a nail in a stethoscope) when running pressure through the line with the other end plugged to narrow down which section of concrete has to be ripped out.

Please keep us informed as to your situation (I promise, I won't miss it again )

[Poconos]

I think Ted is a little mistaken about the nail in the stethescope. He's got a good memory as that post was long ago. That trick was for listening for mechanical noises like subtle bad bearings. However the open end of the stethescope hose is good for finding air leaks if you can get to the leak. As for pressure testing the pipes, I do it every time I close for the winter and open in the spring. You blow the lines clear of water and cap the returns with plugs, then I can disconnect the plumbing at the filter and attach a jig with a tire valve and pressure gauge. Using a compressor I run up the pressure to around 15 psi and then see how long it takes to bleed down. The inline chlorinator will leak a little air but it still will take at least a day for the pressure to hit zero. Doesn't tell where the leak is however, just that there is one which you already are pretty sure of. I saw a water company guy use one of those things that Ted mentioned to find a water line leak. Pipe was about 5 feet down and he missed totally. The landlord had to dig up the whole 40 feet of pipe to find it. Sometimes they work but for small leaks I would think it's questionable. I don't know if there is such a device for finding water leaks based on electrical resistance to ground (at the leak) but I could imagine a device being based on a technique called time domain reflectometry that phone and cable people use to find opens or shorts in their cables.
Something tells me the best and cheapest option may be to simply dig.
Al

[George in Georgia]

Many thanks for the suggestions. I've been away since last Tuesday on a family matter, so the pool has just sat, no pumping. Water loss seems more than the evaporation from a measuring cup left out. Sunday afternoon I ran the pump sourced from the main drain (water level is below the skimmer) for two hours and saw no dectable drop in water level. This is encouraging!! It suggests that the returns are okay.

Today I'm adding water to enable using the skimmer; I'll try the two hour test again. Since the liner is in rotten shape I'd be "happy" to find that a replacement would solve the problem. I'll also continue the bucket test.

If the two hour test is successful I may still pop for a $250 visit from a leak detection company. BTW as far as I know the entire underground plumbing run is under concrete. Ratz!

Here is a link to the two products a Google search uncovered for a leak fixing additive: http://www.fixaleak.com/main.html and
http://www.lo-chlor.com/pool_chemicals/leak_sealer.php

Searching through old threads on leaks in this forum and another one uncovered one responder who'd used such a product in 2005; an email to him has produced no response. If you're out there please respond!