Spa water does run down the pool when filter is on

[henaron]

HI Everyone,

I need help!! The other day the water level for both spa and pool were ok. Then we had a party and Spa water level went down. I added more water but I think I added more than what I'm supposed to. Now, my above ground Spa water does run down to the pool when the filter is on. Which it usually does. Any idea, what the problem might be? Thanks!! Any help will be appreciated!!

 

[Bama Rambler]

The most common reason is the check valve to the spa getting stuck open