Faulty Check Valve ???
I recently saw a Q&A on faulty check valves in swimming pools and I couldn't help but notice a similarity in a problem I am experiencing. My spa drains each time the pool pump is off. In just a few hours it will drain down to the spa jets and I assumed it might be the check valve ( or something stuck in the check valve) Who ever answered the other persons problems seemed to have a very good sense of the inner workings of pool plumbing. If there is any chance I too could call on that persons expertise I would be greatly appreciative. I can provide pictures of my pool equipment if needed.