The AquaFX High Flow High/Low Mechanical Float Valve is an essential component for automatically maintaining precise water levels in your saltwater reef aquarium or associated reservoirs. This robust valve efficiently manages water flow, ensuring a consistent level by allowing a backup supply to enter when the water drops below a pre-set point and then shutting off when the desired level is reached. Constructed from durable, corrosion-free plastics and stainless steel, this float valve is built for longevity in marine environments. It features extra-long mounting stems to accommodate various tank wall thicknesses, an integrated mounting nut, and a sealing gasket to eliminate the need for an external bulkhead. For added control, a blocking device allows the valve to be locked in a closed position, and internal check valves are standard. Available in both a 1/2-inch low-flow option, supplying less than 4 gallons per minute, and a 1-inch high-flow option, capable of delivering over 60 gallons per minute, it caters to diverse system requirements. This AquaFX float valve is ideal for reef aquarists seeking a reliable, low-maintenance solution for auto top-off systems, RO/DI storage reservoirs, or sump level control. Its versatile flow rate options make it suitable for a wide range of setups, from nano tanks needing slow, steady replenishment to very large systems demanding rapid water delivery. With its durable, marine-grade construction, users can depend on trouble-free performance and consistent water level management, crucial for a stable reef environment.