The AQUATOP AP-50 is a powerful but blissfully quiet air pump for aquariums ranging in size from 20 to 50 gallons. Super low energy consumption saves you money, while several models, like the AP-50, are equipped with a control knob for an adjustable flow rate. AQUATOP's AP Series of electric aquarium air pumps allow your aquatic creatures to acquire the oxygen they need in order to thrive. An air pump system adds air bubbles, creates current and agitates the water to help in filtration. This is where the quiet hum noise of most aquarums comes from. An air pump also aids in maintaining stable and healthy pH levels inside the aquarium.