The theory of the flow reversal will work but pool return inlets are not made to be suction inlets. In an existing pool you could get the same effect by pulling all your water thru the skimmers and returning the water to the return inlets pointed towards the bottom of the pool floor. It is more efficient from a heating stand point to have the hot water return into the pool from the floor because as heat rises it will heat more water. The best way to do this is to have an infloor cleaning system that returns hot water to the cleaning heads.