In ground pool. The last couple of months I've noticed air bubbles at the pool water returns. The pump suction basket empties out every night. I've replaced the suction basket o-ring. Done the soap test on all the fittings/joints/strainer drain plug, done the running water test too and can't seem to locate the leak. Looked at the suction strainers in the pool and don't see a whirlpool. I've also isolated them and just pulled water out of the spa and still air bubbles in the pool. Could the leak be coming from the pump itself? About two years ago I replaced the motor and mechanical seal. Everything good up until a couple of months ago. Any help appreciated.