To clarify, make sure all of the flocculant has been allowed to settle to the bottom and vacuum it all to WASTE. Only once you are sure that all the flocc has been removed (as much as possible), then can you return to running your water through your filter. Flocc is like glue. If it gets in your sand filter it will gum it all up. It's sort of why we don't recommend it on this site. It has all sorts of nasty, nasty side effects. And the pool store doesn't care because you will be back in buying replacement sand/filter from them (CHA-CHING!).