I've been struggling with the spa draining into the pool overnight (when the pump is off) for a month or so now. I'm not adding any water, so I don't think it's a leak. The spa return line has a Pentair check valve that is glued-in. I thought my piping "looked" good, but now I see that they glued everything with no space to cut out parts and glue in new parts with unions.
My pool is only a year old, so I went back to the pool company to request service. The guy came out and installed a Jandy check valve on a vertical downward flow orientation, which the instruction sheet clearly illustrates as a WRONG installation. Nevertheless, with the two checks in series, I thought maybe this would help. It did not.
Supposedly they came back out yesterday, although I have not been able to get them to tell me what they did. I assumed they were going to inspect the automated return and drain valves. I noticed my spillover flow was much lower than before, so I think that's what they did, but the spa still drained overnight.
I can work on this myself, but I was trying to make "them" fix it. I'm running short on patience now, so I have a few questions. If I find out that the valves checked-out ok, and if I believe that I don't have reverse flow through two check valves in series, what is the next step?
Each morning the level is still above the jets (fed from the spa return). I don't know if it stops draining at that point, or whether it just drains that much in 8 hours. I'm thinking about draining it down beneath the jets and leaving the pump off. My thought process is that if the leak is on the "return side", the level won't drop further. If it's on the "drain" side, the level will continue to drop. Is this sound reasoning?
I also read about air leaks being a potential source of this problem. Can someone explain how this works? I clean my pump basket weekly, and I "think" the basket used to stay full of water while I cleaned the strainer, but it drains pretty quickly now. If that's true, is this a clue that something is leaking on the "drain" side?
Thanks for any help!