I have a 18x33 inground oval pool. Approx 30,000 gal. I have been losing about 3/4 inch {about 300 gal] a day. Two pool guys have checked and I had an experienced diver spend two hrs in the pool. He checked all the plumbing, including the main drain, the steps and all the return lines. No one can find any reason. There are no soft spots or other telltale signs in the liner. I wish someone would invent a "stop leak" to run in the pool. Has anyone had this?