Finding leak in Inground pool - started mid summer

I am now going to attempt to find the source of a leak in my inground pool.

The pool builders (built about 10 years ago prior to our purchase of the house, and are not very honest) said that the pool can leak through the gunite. However, the company that I use to service the pool (open/close, repair) said that gunite will not leak and that any leak that occurs will be from the drain, skimmer, pump system. I believe that this is the case. However they are resistent to work on a pool that they did not build. Therefore, I am going to attempt to do this leak detection myself.

This year, the pool did not lose anywater from opening (May 15th), until last week. Last week I noticed that the pool began losing water. I want to check the hydrostatic valve being stuck open. I have SCUBA gear and will check the valve for something obvious this weekend (July 15th). If this looks fine, I will check the light and skimmer to see if there is any obvious sucking of water with the pump off. I dont believe that the leak could be coming from anywhere else (but I am open for any ideas).

Last year we had a leak all summer. Initially the pool guys replaced the hydrostatic valve, but that did not fix the leak. They also tested the pump system and did not find any leak. They then said any other leak would be the gunite. They did reseal the light and skimmer.

What type of dye should I use to test for leaking at the Hydrostatic valve.
(where would I get this Dye)?

Is it logical that a hydrostatic valve can get stuck this regularily?

Any other suggestions???


Thanks, -- this site is awesome for use with pools.... thanks!!!!

John

John,
How much water is your pool losing a day?

I just had a problem with my hydrostatic valve causing major water loss. Up to a foot a day. My pool guy actually put a plug over the hydrostatic value entry, and that stopped the leak. He said, if the ground water needs to come up thru, that the plug he put in will pop out.

One way to know for sure if you have a structual leak in the pool, or if its coming from main drain or hydrostaic valve is to shut pool off, plug your skimmers and returns , and see if water still leaks.

One more point to add to last comment.... plug drains, skimmer and return and then do the bucket test to compare water loss. If you lose more in the pool than in the bucket then you have a leak either through the gunite (sounds like fun), light or the hydro valves.

I am losing <1" per day,maybe 3/4max, but definitely more than evaporation. I will try the bucket test to get an accurate measure. I will plug the skimmer and drain and see how that affects the loss.

Have you ever heard of leaking through the gunite wall (without the notice of an actual crack visible)?

Also, do you know how small the leak can be to cause this water loss? (should I be looking for something very minor)? When i hear losing 3 -4 inches plus / day, that is much more than our pool is losing.

But, up till last week, the level did not change at all (except minor evaporation)... But over the last week or so, i need to add 1"+ / every other day.

Thanks,

John

To answer Johns first question of type of dye, someone suggested RIT the clothing dye? Some say phenol red...expensive, Food dye also expensive, can go to a dive shop and get a dye marker and break it up and dissolve to make a bunch, I use stream tracing tablets, I also suggested raw beets. Chop, boil, save deep red water for dye, eat beets.
Al

Hi John, welcome to the forum! Leak detection is an inexact science, what's already been suggested (plug lines and bucket test) is the usual place to start.
I have a suggestion or two for you to try:
Check the inside walls and especially the bottom of the skimmer (s) for hairline cracks - easy enough to do as you'll be plugging them off.
Check the backwash port on your multiport (if you don't have one this will be very hard to do ;) ) for seepage - while you'rre there check for wet spots on the filter pad.

You're not loosing a ton of water/ day so the leak is going to be small, unfortunately that makes it harder to find, if it's not something obvious - however any water loss is too much.
Since I don't know where you are I have to ask about your rainfall this season, lots of flooding like in the NE? If so, all the rain may have prevented you from noticing a leak until last week - also lots of rain might have made the hydrostat pop and perhaps it didn't properly reseal (good thing you've got the SCUBA set).
Please let us know how the tests go - we're falling over each other trying to help :D - Good Luck -- Waste

Thank you to everyone who has been providing assistance to a newbee in the pool care arena.

I have all the suggestions written down and will try to find the solution this weekend and report back my findings.

To answer a couple questions, -- Waste - I am in MA, and we did have a lot of rain. In fact during the non-leak timeframe, i had to drain the pool to get the skimmer from being totally overflowed and overflowing the pool. I do not believe that disguised the leak.

Last year when I just let the pool leak, it stopped at a specific area (which gives me some other areas to focus on - besides just the main drain - hydrostatic valve).

I dont know if this has any bearing, but there has been a significant debris around the main drain (we have two dogs who swim - and shed)... This is still my first area to focus on.

I can check the pump area (in fact will do the testing to see if the leaking stops w/out the pump running). On visual inspection, there is not anything noticable.

Thanks again to all the suggestions, and i will do my best to identify (and then see about repair) the leak.

John

Thank you to all who assisted.

On Saturday, equiped with SCUBA gear and dye, I proceded to the Hydostatic valve. It was working perfectly normally, no leaks, or any problems. From there, I went around the pool and eventually found a very small seperation (gap) on one of the plugged return pipes. I checked this previously, but the leak was tucked underneath and could not be seen without the SCUBA and dye approach.

I found some "Aquamend" epoxy, which set up and cured nicely.

Now, the leak is no more and the pool is in great shape.

Execpt -- the temp is VERY warm - thanks to very hot outside.

Thanks again.

john