Leak detection and repair - suggestions?

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.

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

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.

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:) )

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

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!

An update. Since my last post I've run the pump/filter from the skimmer and from the main drain for 12 hours or more with NO discernably different drop from the bucket test. Loss since my last post is about 1/4 inch, easily accounted for by evaporation. The dogs seem to have drunk from the test bucket; it shows about an inch drop.

Talking to a dealer about a new liner he mentioned that a bit of trash could stop up a liner leak. Sounds reasonable. That could explain the sudden 3 - 4 inch drop, and its "miraculous" cure.

Someone on this or another forum mentioned that plumbing leaks accounted for only about 10% of all leaks. Since my plumbing seems to be all underneath concrete, with no indications of the slabs sinking, perhaps my situation falls into the 90% of leaks, the liner.

Any thoughts from The Collective Pool Brain???

As far as liner leaks go, I know that areas around light niches, steps, etc are common places for leaks. Otherwise, I don't really know what to tell you other than if you let the water just leak out, at least the water level will stop changing when you get to the level of the leak, and hopefully give you an idea of where to look.

Janet

No drop in water level other than evaporative loss after about 18 hours of filtering. Looks like the plumbing is okay. After replacing the liner we should have swimming through most of September, here in the sunny south.

Many thanks for the group's suggestions and moral support through this and my prior green water adventure. When I get the new liner in I'll know how to start off right!

Sorry for the long delay in a response. In the mean time we've gotten two bids on replacement, both from established local companies. After careful comparisons we chose a company with 13 years' experience. Discounting the set-up chemicals to be furnished by the somewhat higher bid, the difference was about $200, plus the lower bid was for a 30 mil liner, vs 20 mil for the slightly higher. BTW, the pool was installed in 1993 and to our knowledge it had its original liner. I'd say we were overdue!

Installation was finished in about 1 1/2 days and went smoothly. The pool is now in use, and is beautiful - crystal clear. We're using up some CaHClO shock while we add NaCl for the SWG, plus NaHCO3 for pH. All that alphabet soup! The CYA is at about 30 ppm after 4 days, can't rush that.

A couple of questions:

The info that came with the liner wants total alkalinity at about 100 ppm, and calcium hardness at 100 ppm minimum. I seem to recall reading either on this site or another similar one that calcium is unnecessary for a vinyl pool. Any comments?

The main drain was cleared of debris when the VGBaker drain cover was installed. Nevertheless flow though it is minimal; if the skimmer is turned off I risk cavitation in the pump. There is an auxilary intake plumbed with the main drain at the same level as the return nozzles, it is presently plugged off with a threaded gasketed plug. Could this be used as a point to pressurize the main drain by shutting off the drain circuit at the pump and then using compressed air at say 25 psi to perhaps dislodge plugging materials? Or should I just leave well enough alone and enjoy my rejuvenated pool.

Many thanks for members' advice and sympathy. At least here near Atlanta we have considerable swim time left; my wife, a native of Florida, says we'll break the ice to take a dip! We'll see about that!

Quote:

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Originally Posted by George in Georgia

The info that came with the liner wants total alkalinity at about 100 ppm, and calcium hardness at 100 ppm minimum. I seem to recall reading either on this site or another similar one that calcium is unnecessary for a vinyl pool. Any comments?

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Regarding the issue of calcium in vinyl pools--that info was probably just advice the printer was told, rather than based on any good reason....HOWEVER.... In all actuality, it won't hurt for CH to be 100, it's easy to get it there if you're using cal-hypo for chlorination or shocking, and it's possible that there's some form of calcium in the makeup of the liner that you have that would require it to be present in the water. If the warranty ever might become an issue, then I guess it would be better to keep the water levels where they want them, even if there's no solid reasoning behind it! :)

Janet

It sounds like you have a partial blockage of the main drain as you said there is some flow. Therefore I suspect compressed air won't do much. It is high pressure, low volume. Something like a shop vac in blow mode with high volume won't have the pressure to blow the water out with that much water depth. However.....how about rigging a fitting to that auxiliary intake to adapt a garden hose and use water to flush backwards? You have the pressure, fair volume, and the mass of the water working against whatever is plugging the line. If you want more volume of water, you can make the fitting adapt to two or three garden hoses to get more flow from multiple sources. PVC is cheap and you can make all kinds of crazy adapters. Let your imagination run wild in the Home Depot plumbing section.
Al

Interesting ideas, Poconos!

BTW, I mentioned the problem to the good folks who installed the new liner, and Buster (no kiddin') speculated that the extra suction inlet might be for a water powered cleaner. I've toyed with the idea of connecting the pool vacuum hose to this inlet to see what might happen. If it is indeed plumbed to the main drain, that suction might move the clog to the skimmer box. I can't see how it could hurt.

I guess the only danger may be jamming the obstruction tighter. Would be nice if you could suck it out the way it came in.
Al