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 1/4" outputs or valves that can be teed off twice to power up to eight WaterFarm units. In addition, growers who use the Dual Diaphragm air pump can count on it to reliably oxygenate their reservoir with air stones.