We have had to add water to our pool all summer and have determined that we have a leak somewhere. We turned the pump off and plugged the in and out and the water has been gradually leaking out. We cannot find the leak. There is a damp place on the ground below the retaining wall which was built to level the ground for the pool, but we can't find a leak in the pool any where near it. We do have some sunken in places in the sand underneath this spot. Should we just let the water continue to leak out over the winter and just replace the liner? It is 5 or 6 years old. I guess we probably have a cheap liner since it is what came with the pool originally. We haven't talked to our pool store to see if they can detect a leak because I honestly don't have any faith in them. Any suggestions?