The V4 valve allows a standard aerator pump to be mounted directly to the valve body for both filling and recirculation duties, thus eliminating the need for 2 separate pumps and additional plumbing. When in the "FILL" position, the valve will close the livewell drain side of the valve so the pump has free access to fresh outside water. Once the livewell is full, the valve is placed in the "RECIRC" position to close the drain and allow full recirculation of the livewell water. Occasionally returning to the "FILL" position will keep the livewell topped off and freshened. The "EMPTY" position allows gravity draining with the pump off.