Strong, reliable and quiet, the General Hydroponics® Dual-Diaphragm Air Pump is designed specifically for use in hydroponics. It has four adjustable 1/4-inch (25-millimeter) outputs that can be T'd off to power up to twelve air-driven hydroponic growing systems such as the General Hydroponics WaterFarm®. Capable of pumping 320 gallons per hour (20 liters per minute), this high-output air pump can also be used to reliably oxygenate reservoirs with air stones.