Help my pool is leaking

We lost about three inches of water overnight...and it is still dropping. We know we had a leak at the bAck of our light. The pool company came and put epoxy and permetex gasket maker over it and then my husband put more. We let it cure for two days. Fill to just above light and let it sit to see if leak continued. No water loss so we continued to fill. We filled slowly over next two days with what seemed as not water loss until we go to skimmers. Filled to skimmers last night and then overnight lost three inches of water in our 18'x36 rectangular pool. It seemed again to stop and now is dropping again. Another inch. Any suggestions on how to identify where pool is leaking?

Hi and Welcome to the forum. Also thanks for subscribing. We'll do our best to help.
I'm going to make a couple assumptions that it is a liner pool and inground. Also, do you notice any change in the leak with the pump on or off? One of the ways to possibly get a grasp on the level location of the leak is to watch the leak rate. To do this you need to measure the water level as accurately as you can and record the level and time. You can make accurate level measurements with a ruler and place it in the same spot each time. Could be a mark on a step for example. If you can measure to 1/16" that would be great. Leak rate is determined by dividing the level change by the time interval in hours wi give inches per hour. The deeper the water above the leak point, the greater the leak RATE. This is just because of the water pressure increasing with depth. As the level drops and approaches the level of the leak the rate will slow and eventually stop at the leak level. If the level drops a foot or so with no change in the rate, as was my case, it would indicate a deep leak as mine was a cut in the liner at the bottom of the deep end. In your case it almost sounds like a skimmer problem. First thing is to eliminate the piping, both the skimmer line and the return lines. Plug the ports and see if the leak continues. Skimmer can be plugged by a 'Gizmo' and the returns by plugs that are available at pool stores. The Gizmo is a plastic 'bottle' type thing that screws into the pipe at the bottom and is usually used for winterizing. In lieu of a Gizmo you can also use a plug on the pipe at the skimmer bottom or even make a plug from PVC pipe parts. Another thing to try is dye testing. I've never used marker dyes from a dive shop but it should make a nice cheap dye. I've used dye marker tablets which are probably something similar. I've also suggested boiling raw beets for a concentrated, harmless red dye. You have to slowly squirt this stuff around the suspected leak places and see if it gets sucked in. Must go real slow to not stir up the water. You'll get the hang of it. Check the skimmer plate too and the faceplates around the return jets. The pinch seal around the stairs is another favorite leak location. Let's see where this leads you. If you have to start checking the liner with dye I have suggestions for that too.
Al

I have a couple of questions.

Do you see any soft damp wet spots on the ground anywhere around the pool? Say a soft spot exists near the back corner, that would be a pretty good clue you have a leak in that area.

Have any trees or bushes mysteriously gone dead? I discovered a leak that way once. A leak in the bottom got to a spruce tree.

Did you have any limbs fall on the cover during the winter, like say some ice caused some limbs to fall on the cover. That happened to me two winters ago. It wasn't until June that I noticed the level falling and discovered two small tears in the liner wall right where the limbs had fallen.

Good luck.

Al and Manslick thanks for the suggestions so far.

My pool is inground and does have a vinyl liner. The liner was just replaced two weeks ago by the company that put our pool in 10 years ago. We have been having some small leak problems that last few years such as a small tear in the liner and the leak behind the light in the conduit box. We thought we had them fixed...not so sure now but we have never had anything leak at this rate since the installation of this new liner and a new drain cover.

We lost about 3 more inches since 6pm yesterday (to this morning) I have been putting a piece of tape on the liner by the steps to gauge the leak but have not been timing it. I will do that starting now. Since it has continued to leak below the skimmers my guess is that it is not in the skimmers because we turned them off yesterday morning because the water had dropped below it and were sucking air yesterday am.

So since the leak continues below the skimmer would you still plug the skimmer and the return lines? I am guessing yes to at least rule that out?

Thanks again for the advice! When we were first putting in our pool I found this site and read up schematics and plumbing line sizes etc to talk to our pool company about. It was very helpful! But then I had a computer crash and got busy with life and didn't look for the site again until now. So nice to have experience of others to get advice as sometimes pool co keeps pointing us back in the same direction but without any resolution!

Angela

First, since the liner was put in only 2 weeks ago, get the installer back. Quite possibly he overlooked something like tightening all the pinch strips on the stairs. That would be simple. Just because it didn't seem to leak immediately doesn't let him off the hook in my opinion. If the liner was stressed during install maybe a seam let go or maybe a thin spot in the liner did the same. From what you said the skimmer is not the problem. If the water is still above the returns, plug them.
Al