I have a pebble tech based pool with a raised spa to the side that waterfalls back into the pool i.e. while the pump/filter is running, the spa is designed to overflow like a small waterfall into the pool.
The problem: I notice that every morning (the pump runs 9am through 4pm), our spa level is matching the level of the pool. The spa is a built in that's raised 12-18 inches or so above the pool. As soon as the pump comes on, its set to return through the spa and pool, so within a few minutes, the spa is back up again. I'm assuming the water is leaking into the pool, since the pool level goes up, through a valve each evening and not draining away somewhere else. Its been going on like this for a few months now. I tried rebuilding the jandy valves with new orings and such. But to no avail.
In a nutshell, the raised spa drains down overnight to the pool level.
I know installing a check valve in between the spa drain and the pump inlet would fix it, but I don't have room.
Q1: Can I install a check valve "AFTER" the main circ pump? to fix this issue?
Q2: What kind of check valve do I need? Spring check or swing check?