My wc goes like this. 2" pool hose from the FOWLR sump to the drain. Then a 3,000 gph pump is used to transfer water from the reef sump to refill the FOWLR sump, then to pump fresh saltwater from the mixing container to fill the reef sump. This way I can reuse the relatively clean reef water for a wc on the FOWLR tanks. Starting a siphon with the 2" hose is how I found out how important it is to drain all of the old water from the hose. :-[ I thought I was going to die.