Leak detection and repair - suggestions?

[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!

[George in Georgia]

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???

[aylad]

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

[George in Georgia]

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!

[George in Georgia]

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!

[aylad]

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?

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

[Poconos]

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