My 23yr old swimming pool (just inherited) appears to be leaking water (losing slightly less than 1/2" daily) and I've noticed while running the 1.5HP hayward pump that randomly I see a single, large bubble float up from the main drain along with micro-bubbles from the returns. This is with the pump pulling from the skimmer and the main drain with the filter engaged. The system has been running like this for several days and the behavior continues. I can't find any leaking water at the pipes above ground or from any of the equipment and cannot find any wet ground around the pool, but most of that area is covered in concrete so it would be hard to spot.
Any ideas?
Any ideas?