Buying task · Air pumps and aeration
Aquarium air pumps and aeration
What an air pump does for gas exchange, how to read flow and dB figures, why 230 V pumps don't belong on US mains, and what battery-backup pumps claim.
Short answer
An air pump helps mainly by moving the water surface, which is where gas exchange happens.[1] Size it from the maker's flow figure and suggested tank size, buy the variant rated 120 V / 60 Hz, and read any dB figure as that publisher's own number, not a cross-brand ranking. If outages are a worry, a battery-backup pump can bridge one, for as long as its maker claims.
What an air pump does
An air pump pushes air through airline tubing to an air stone or a sponge filter. The rising bubbles move water and break the surface. Aquarium Co-Op says that good surface agitation is key to gas exchange.[1] A 2020 study of 54-liter aquariums found that oxygen uptake from the air was strongly influenced by water flow and by how much open surface was available.[2]
So a pump is not always required. Tetra says its Whisper Power Filter adds oxygen by breaking the surface as it returns water, and that an air pump is not needed with it.[3] Where a pump earns its place is with sponge filters, in tanks with little surface movement and as backup when the power fails.
The decisions, in order
1. Flow and tank size. Makers publish flow in liters per minute or per hour. Tetra lists 0.5 L/min for the Whisper 10 up to 3.3 L/min for the Whisper 100,[4] and Fluval lists 90-110 L/h for its A101 and 330-370 L/h for its A402.[5] These are maker figures with no stated test depth. Depth matters: FishLab reports that it affected both air output and noise, especially for pumps made for small tanks.[6] The flow guide converts units and explains "for 40 gallons" labels.
2. Outlets. One outlet per air stone or sponge filter is simplest. Tetra says a dual-port pump will be very loud unless airline is fitted to both ports, and supplies a T connector to join them.[3] Fluval gives each A Series outlet its own flow dial.[5]
3. Noise, read carefully. Aquarium Co-Op publishes 43.5 dB for its pump with no distance or method,[7] and Fluval gives "under" figures without a method.[5] FishLab held its meter 6 inches from each pump,[6] while ModestFish placed its meter next to each pump on a hard surface.[8] Those numbers cannot be merged into one ranking. The noise figures guide explains what each one means.
4. The voltage variant. Sicce rates its AIRLIGHT pumps at 230-240 V / 50 Hz only,[9] and EHEIM's air100 page lists 50 Hz ratings.[10] Fluval, by contrast, lists its A202 at 3 W on 120 V / 60 Hz.[5] Check the rating on the exact variant, not the model name.
5. Backup for outages. Aquarium Co-Op says its battery-backup pump switches to its built-in lithium-ion battery when power is lost, and states about 20 hours of continuous running or 40 hours in Power Save mode.[7] Those are maker claims, not independent runtimes. It also says the pump is not shipped to Hawaii or Alaska.[7]
Every page on air pumps
Guides
- Do air bubbles add oxygen? What surface movement does
- Air pump flow explained: L/min, L/h, depth and "for 40 gallons"
- Air pump dB figures: what they mean and why they don't compare
- Battery-backup air pumps: runtime claims, Power Save and lithium care
- Air pump above or below the tank? Back-siphoning and check valves
Tank and trip pages
Comparisons and shortlists. Not yet. None of the air pumps we have researched so far meets our catalog bar: an exact model with a 120 V / 60 Hz rating, a safety certification mark stated by the maker or a certifier, and a seller we can tie to the brand. We would rather list none than force one.
How to choose
Until a pump meets that bar, use this checklist on any listing:
- A model number and a maker page that states the voltage and frequency (120 V / 60 Hz) for the variant you are buying.
- A certification mark from a recognized lab on the unit's label, not just the box or the listing title. Tetra, for example, states that its Whisper line is UL listed but gives no file number per model, so check the label of the exact unit.[4] Our guide to verifying a UL or ETL listing shows how.
- A flow figure and suggested tank size from the maker, read as a rough guide.
- Outlets that match the air stones or sponge filters you will run.
- Tubing size: Fluval lists 3/16 in hose for its A Series, while EHEIM lists 4 mm.[5][10] See tubing and check valves.
Key terms
Airflow, liters per minute, backpressure, diaphragm pump, decibel, manufacturer figure, independent measurement and Power Save mode.
Everything in this topic
Guides
- Air pump flow explainedLets you compare air pump flow figures on the same unit and judge how much a maker's tank-size label tells you.
- Air pump noise figures, explainedShows how to read a published dB figure for an air pump and what you can actually do to choose and run a quieter one.
- Battery-backup air pumpsHelps you judge what a battery-backup air pump covers during a power cut and what its runtime figures do and don't promise.
- Do air bubbles add oxygen to an aquarium?Helps you decide whether a tank needs an air pump or whether surface movement from the filter already does the job.
Common questions
How do I convert L/min to L/h?
Multiply by 60. Tetra's 0.5 L/min for the Whisper 10 is 30 L/h; Fluval's 90-110 L/h for the A101 is about 1.5-1.8 L/min. More in Air pump flow explained
Does a deeper tank reduce air pump output?
FishLab reports that tank depth affected both air output and noise in its own measurements, especially for pumps made for small tanks. More in Air pump flow explained
What does 'for tanks up to 40 gallons' mean on an air pump?
It is the maker's suggested tank size. Tetra, for example, offers Whisper pumps for 10 to 100 gallon tanks, but those labels are suggestions, not measured flow. More in Air pump flow explained
Can I compare flow numbers from two different makers?
Only roughly. Makers rarely state the depth or method behind a flow figure, so treat two makers' numbers as a starting point, not a ranking. More in Air pump flow explained
Is more airflow always better?
No. More flow means more bubbles and usually more noise; match the pump to what it drives, such as one air stone or a sponge filter, and use the outlet's flow control if it has one. More in Air pump flow explained
Which aquarium air pump is the quietest?
No source lets us rank pumps across publishers, because each measured noise differently. Compare figures only within one publisher's results, such as FishLab's. More in Air pump noise figures, explained
Why did my air pump suddenly get loud?
Tetra says a Whisper pump that gets very loud or stops making air may have a worn rubber diaphragm, a wear part not covered by its warranty. Do not open mains-powered equipment; contact the maker. More in Air pump noise figures, explained
Why is my dual-outlet pump so loud?
Tetra says a dual-port pump will be very loud unless airline is fitted to both ports; its pumps come with a T connector to join the two. More in Air pump noise figures, explained
Questions
Do air bubbles add oxygen to an aquarium?
Mostly indirectly. Aquarium Co-Op says bubbles create water movement and surface agitation, which is key to gas exchange, and a 2020 lab study found oxygen uptake from the air depended strongly on water flow and open surface. More in do air bubbles add oxygen?[1][2]
Which air pump is the quietest?
Published dB figures cannot answer that across brands. FishLab held its meter 6 inches from each pump, ModestFish placed its meter next to the pump, and Aquarium Co-Op and Fluval state no method at all. Compare figures only within one publisher's own test.[6][8][7][5]
Why is my air pump suddenly loud?
Tetra says a Whisper pump that stops producing air or gets very loud may have a worn rubber diaphragm, a wear part, and that a dual-port pump is very loud unless airline is fitted to both ports. Do not open a mains-powered pump yourself.[3]
Can I use a 230 V air pump in the US with a plug adapter?
No. A plug adapter changes the plug shape, not the voltage. Some pumps are made only for 230-240 V / 50 Hz mains, such as Sicce's AIRLIGHT range, and EHEIM's air100 page lists 50 Hz ratings only. Choose a variant rated 120 V / 60 Hz.[9][10]
How long does a battery-backup air pump run?
Only the maker's figures exist. Aquarium Co-Op states about 20 hours of continuous running, or 40 hours in Power Save mode, for current units, and 8 and 16 hours for units sold before August 1, 2024. See battery-backup air pumps.[7]