Hello.. So, we have a large inground pool built prob 30yrs ago. It has 2 cracks that are leaking some water (used dye). Not sure on the volume yet. I think 1 light is also leaking. Those leaks i will fix but i have a much larger leak somewhere else. Its leaking weather pump is on or off. More when running. No air anywhere in system from suction side. But.... When i turn off pump, regardless for length of time, every return jet is sucking water backwards. To clarify.. Pump is off... 1 hour or 48 hours makes no difference. I can take the dye & every return nozzle in the pool will suck the dye into the return. Ive checked the drain line where it connects to the waste water going out to sewer line, & its dry. Pump doesnt ever get any air or lose prime. I started digging the return line from pump out towards pool, because i was sure the leak was on return line & it runs directly under a stupid tree my mom planted years ago trying to hide the equipment from view. But now im not sure. Ugh.. Im only like 5-6 ' from tree, & i would have thought i should see wet dirt & sand by now, but no. Im losing 2-3 " of water in 24hrs. I stopped my digging last night to see how far the level is gonna drop. Any ideas would be great. Im stumped on the water being sucked backwards though. Im gonna make some contraption so i can use the dye to look at both drains. Thanks for all ideas.