General Hydroponics Dual Diaphragm air pump is the only air pump in the world that is manufactured exclusively for use with hydroponics systems. This high output pump (394 gph/ 24,800 cc/minute capacities) has four adjustable 3/16" outputs or valves that can be teed off to power up to twelve additional WaterFarm units. In addition, growers who use our Dual Diaphragm air pump can use it to reliably oxygenate their reservoir with air stones.