Okay, our filter required the purchase of a key assembly and not just a spider gasket (Hayward SP714TX). So, we put the new one on and still had water coming back into the pool on waste and some on backwash. When going through the different cycles, the gasket part came loose and we had to take it back off and correct the positioning on it because we were losing water on filter.

So, what else could it be? I'm stumped - there is nothing else in the tank that changes the water flow on the different cycles is there? I can't see that I need a whole new multiport valve because the bulk of it is the key assembly that we replaced which did not solve the problem. I hope they take it back - it was $37.

What else do I need to look for to stop this water from returning to the pool on waste?

Thanks!