I have a vinyl liner 32,0000 gallon in-ground pool. It is 20' x 40', with an in-wall light and steps. The liner is less than 5 years old. I have a 1 1/2 hp Hayward pump and DE filter. I have 2 skimmers and 3 returns. My skimmer inlet and MD are in the same skimmer. The pool is 8 1/2 feet deep with a main drain.
I have been losing 2000-3000 gallons of water a day. I can't see where it is wet anywhere around the pool or pump.
I had a professional leak detector come out. He checked all lines, drains, equipment and liner and could not find a leak. Since we had a leak behind the light a couple of years ago, his only suggestion was for us to have someone pull the light and re-apply silicone around the conduit.
I finally found a person willing to come out and re-silicone it. He instructed me to drain the water half way down the light. I did so, but by morning, the pool leaked so much that the water level was below the light. The pool repairman told me that it had to be sealed with a special pool silicone, but when the "boy" came to my house, he used a silicone purchased from Ace hardware, which concerned me.
We live in the country and only have well water, so all water that we put in the pool must be hauled by truck. We ordered 18000 gallons of water which took 3 loads over a two day period because the driver had to drive 3 hours one way to get it here. I was so excited to come home to a full swimming pool yesterday!
When I got up this morning, my husband informed me that we lost around 5 inches of water over night (approximately 2500 gallons). I haven't been able to determine if we lose more when it is running or not running. I have done all the water tests by marking the water level, dye tests, shutting off skimmers, returns, and plugging the main drain off in the skimmer.
Before we got the water hauled it leaked down to a few inches below the light, but the weather was really hot and humid during this period and the pool was not running. My husband and I disagree as to whether the pool was still leaking or simply evaporation.
I now have the pool shut off and the MD plugged in the skimmer. Even though the leak detector said it was not the MD, I think that it might be. (Mainly because he didn't dive to the bottom of the pool and seal the main drain in order to pressure test it. He simply squirted air into it and said he didn't think it was the MD.) I saw on a post that you can purchase a MD cover to block off the MD. I have searched and searched on the internet and cannot find this adapter plate that they referred to.
If anyone has any ideas as to what the problem is and/or can help me find this adapter plate I would be very appreciative. I can't afford to spend another $1500 for water that will be gone in a few days. The water level is almost below the skimmers again and its only been one day.