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. Any additional fill or recirculation pump is optional and only becomes a true back-up to the main system pump. Once the system is put into the "AUTO" position and the pump turned on, all livewell functions are handled so the angler can concentrate on fishing. Ideally used in walleye boats or other high profile boats for drain control and livewell management. Accepts mounting of one standard aerator pump for both filling and recirculation. Includes closed recirculation mode which allows addition of optional pump-out systemProvides FILL / EMPTY / RECIRC modes