Hi everyone. I have an inground fiberglass pool (called an "iPool2" by San Juan Pools). It has a small spa on one end and the pool part has an infinity edge. This is a weird pool because there is no skimmer. I have three pumps servicing the pool; one is the main pump which handles the pool and spa suction and return lines, another pump which runs the polaris and a third that pumps the water captured off the infinity edge in an "overflow basin" back into the main pool. The pool and spa have two main valves which control A) the amount of suction going to each area (spa or pool) and B) the amount of water going to each area from the return lines. Although I've had three pool companies come out and test for leaks (pressure testing lines and sonar test) and all say there is no leak. However, the pool still looses water (maybe an inch every other day and the pool holds 9,000 gallons) and especially whenever it rains. We just had a really hard rain (2-3") and the water in the spa is almost completely gone. The pool, however, is full and water is even flowing out of the infinity "overflow basin" into the yard. Whenever this happens, all I know to do is cut off all suction on the spa side and put 100% of the water coming from the return lines back into the spa. This way the pool area will have 100% of the suction and 0% of the return. The spa will fill back up rather quickly this way but the overall water level of the pool is down and it normally takes 3-4 hours to fill it back up.
Here is a rough diagram I made of the pool. Any thoughts?