I have a fiberglass walled, gunite bottom inground pool. I have had a leak for some time which causes me to loose about 3/8" of water per 24 hours. The leak isn't affected by whether or not the pool pump is running. Evaporation isn't the issue either.
Last week I decided to get serious about locating the leak, I decided to let the water drop until it stopped, thinking it would help locate the leak or at least the level of the leak. The leak continued each day, so I decided to speed it up, thinking the pool light might be the issue. Sure enough when it got to the level of the pvc connection behind the light, the water level stabilized. I used some epoxy putty from the pool store, thinking my problem was solved. I added some water until the pool light was covered and waited, the leak seemed to be fixed. I went ahead and refilled the pool, the next day I noticed the water level had dropped again. Using the same method as before I let it drop on it's own, until it was below the skimmers and the return lines. I pumped more water out about 2" each time and waited. Finally the water stabilized again, about 3" above the pool light. So it seems the first leak was fixed.
I figure the leak must be somewhere close to the water line, where the water line stopped dropping. I used some leak dye to check for leaks. The walls of my pool are fiberglass panels, each about 8' in length. The are bolted together from the backside with some type of gasket material between panel. It appears to be a silicone (?) type of gasket. There are no other fittings etc. at the suspected leak level. I added an inch of water to the pool and checked each gasket seam as well as the steps area. So far no luck it finding the leak.
Could the leak be so small that the dye isn't effective in locating the leak? Any suggestions?