Best Aquarium Air Pumps: Quiet, Adjustable and Battery Backup

Tetra's Whisper line comes in 10, 20, 40, 60 and 100 gallon sizes. The listing says the 10, 20 and 40 gallon pumps have one air outlet and the 60 and 100 gallon pumps have two. This 20 to 40 gallon model has the push to drive a sponge filter or an air stone in a standard-height tank, and Tetra describes a suspended motor inside a dome with sound-dampening chambers and rubber feet to cut noise and vibration.

It has no flow knob. If you need less air, for a betta or a planted tank where you want little surface agitation, add an inexpensive airline valve, or choose the adjustable hygger below.

The 30 to 60 gallon Whisper is the size to buy when you want two things running from one pump, such as a Hikari X-Large sponge filter and an air stone in a 55 gallon tank, or two small sponges in two quarantine tanks on the same shelf. The listing gives it two outlets and the same suspended-motor, dome design as the smaller Whisper.

Add a check valve on each line so tank water cannot siphon back into the pump when the power goes out, and a small valve on each if you want to balance the airflow between the two.

hygger's quiet pump has two outlets and a knob that sets total airflow up to 80 gallons per hour of air, according to the listing, on 3.5 W. The listing rates it for tanks up to 120 gallons with water no deeper than 3.9 feet, includes a check valve and an air stone, and gives a 2-year warranty.

The knob is the reason to choose it. A betta tank with a sponge filter needs a trickle of air, and a cheap fixed pump either blasts the water or needs a separate valve. Treat the under-30 dB claim as the seller's; any air pump is quietest on a soft pad and away from the tank stand, where cabinets amplify hum.

Uniclife's listing is more specific than most: 64 gallons per hour of air, a pressure of 0.016 MPa, 4 W, and noise of 25 dB on low rising to 45 dB on high, about the hum of a refrigerator in the seller's words. It includes everything to start: two air stones, 6.5 feet of tubing, two check valves and two connectors.

For a 10 to 40 gallon tank running a sponge filter and an air stone, it is a sound budget pick. Pressure is the limit to know: the deeper the water, the more pressure a pump needs to push air out at the bottom.

When the power fails, filters stop and oxygen in the water starts to fall, fastest in warm, crowded tanks. This pump runs from the wall normally and, according to its listing, switches to a built-in 2,200 mAh lithium battery on its own when the power drops. The listing claims 40 to 45 hours in continuous mode and 70 to 80 hours in intermittent mode, at 2 W and 30 gallons per hour of air.

Leave it running in the tank all the time, with an air stone or a small sponge filter, so it is already working when an outage starts. That also keeps a sponge seeded with bacteria. For tiny tanks, hygger's 1.5 W mini pump is quieter still, but hygger says it is for small air stones only, not sponge filters.