Like the V2, the V3 is a reversible check valve that allows a single pump to not only perform the basic livewell functions necessary to keep your catch alive, but does it in a passive or automatic manner. It also has a third closed "RECIRC" position. When the first fish is caught, place the valve in the "AUTO" position and turn on the pump. When the boat is off plane the pump will recirculate and aerate the livewell water and simultaneously blend in a portion of fresh lake water. Used livewell water is expelled out the overflow as fresh water enters to prevent any ammonia build up. When the boat is put on plane, the valve's check flapper will prevent water loss out the drain, and allow the pump to continue its recirculation duties. Any water lost out the overflow while running on plane is automatically made up when the boat is brought off plane at the next fishing location. All this is accomplished without any operator assistance. For those times when outside water is not wanted or available, such as, adding ice, livewell additives, going through locks, traveling to out of water weigh-ins, dockside refueling or using our optional Pump-out /Venturi Aerator, place the valve in the "RECIRC" position. To empty, simply turn off the pump and move the valve to the "EMPTY" position for gravity draining. Ideally used in bassboats, flats boats, and other low profile boats for Automatic drain control and livewell management.Accepts mounting of one standard aerator pump for both filling and recirculationIncludes closed recirculation mode which allows addition of optional pump-out system.Provides RECIRC / EMPTY / AUTO modes MFG# MPV-03-RN01 MPV03RN01 UPC# 784176010130