Hi, I've a spa connected to my pool (not heated), a couple of days ago i noticed that when the pool pump shuts off, the water in the spa drains about 1/2 way (i don't think there's a leak, because i don't have to regularly put water in the pool, i think the water from the spa is going back to the pool) i don't know why this has been goind on, and if someone could help i would really appreciate it.

Also there are a couple of valves that control the pool, maybe one of them is the problem, but i don't know what each one does, could someone explain to me what each one does, and which ones i should leave on?

*there are valves named: floor system, spa spillover , main drain, spa drain, and skimmer.

*I have tried to turn on and off some of the valves, but the pool vaccum shuts down.
1 day ago
Additional Details
1 day ago

Are the main drain and spa drains suppose to be on at the same time? (only the spa drain is turned on at the time, but if i turn if off the little waterfool coming from the spa and going to the pool shuts off, if i turn on the main drain instead the waterfall turns back on but the vaccum doesn't work!

If someone that knows about this has any suggestions i would appreciate it, thank you!
Should skimmer be on with main and spa drain? it seems that vacuum loses pressure!