Mystery leak in vinyl IG pool

[quietcountry]

I have a leak in my vinyl, in-ground pool. The pool is 11 years old, indoors, 15,000 gallon and I keep the cover on it most of the time. This is the second leak in 14 months. Last year trying to fix the leak, I had the fiberglass steps re-caulked, a new gasket for the skimmer, a new gasket for the floor drain, a new gasket for the light, and finally a patch for the very small hole in the vinyl near the return jet. They put a nice patch on that leak.

This year the water leaks about 3/4" per day till the water level reaches 1 1/2 inches below the return jets and stays there. The water leaks till that point if the pump is running or not. As the water approaches this level, the rate of loss slows.

The fellow who finally found last year's leak by the returns could not find the leak this year. He used food color and syringe.

His thinking was to drain the water about 3 inches below where the water stops leaking and re-caulk the steps.

Any suggestions or comments would be much appreciated. Very frustrated.

Larry

 

[dmanb2b]

Welcome to TFP. I almost guarantee the leak is somewhere at the water level where the loss stops...ie 1.5" below the return jet. Is it 1.5" below the entire return, or is the water stopping 1.5" below the top of the return jet? Either way, inspect the liner and all plumbing at or around that water level.

Here is a good atricle in pool school that may help you

pool-school/leak_detection

 

[swimcmp]

Check the conduit for the light. This is a very likely possibility for a leak that will go unfound for a long time since most don't believe they will leak. Look at your water level in comparison to your light. If you take the light out of the niche look at the water level in the niche and where the conduit is.

 

[quietcountry]

The water stops leaking when it is about 1 1/2" below the return jet. I never thought to look at the conduit for the light. The water stops leaking about one foot about the light. We did a dye test around the plate for the light fixture and did not find any obvious leaks. I am going to drain the pool about 6" below the level where the water stops leaking and try resealing the steps.

 

[swimcmp]

The conduit could be leaking anywhere along it. If it was done with gray pvc the pipe is in 10' lengths so you could have a leak at a coupling.

 

[quietcountry]

OK, It sounds like I should take the light out of the niche and try a dye test by the conduit. Thank you for the advice.

 

[swimcmp]

You will have to get your water level up for a dye test to show you any result. We had a pool that leaked couldn't find it, had a diver get in remove the light and dye tested. Apparently when the pool was built the conduit wasn't glued into the niche. Put a cord stopper on the cord and silicone as an added safety. It hasn't leaked since.