Attached SPA drains down

[tlapp]

My attached SPA is draining down about 2 inches a night after the pool pump is off for the day. After about three weeks it is now below all fixtures; jets, return and light. This has happened before and stopped for some unknown reason. Maybe valves were leaking by and reseated after using the SPA?? Is it possible for water to drain down to where I described, which is down below the pool level, by a valve leaking by? And where does the water go? It is not going back into the pool because the pool level has remained steady.

[Denniswiseman]

Hi and welcome
I would suspect a faulty non return valve
Images showing the relation of spa to pool and set up would help

[tlapp]

Thanks! so where does the water from the SPA go if pool stays the same

[Denniswiseman]

Unless you have an overflow
I doubt the pool level stays the same, it's just the amount it rises isn't noticeable because the quantity of water being returned is spread over the entire pool
What is the surface area of your pool and the volume of water in the spa that you are losing?
Please supply some images so we can better understand your layout