i have a hayward sand filter with a multi port valve. We replaced the valve and the sand this spring And replaced all o-rings. I used floc last night and when Inwent to vacuum to waste this morning the jet was returning dirty water to the pool. we are at a loss. The pump is strong and working properly. No leaks when it is in filter or recirculate. Any suggestions? We took the valve off again this morning and checked everyting. It all looks good.