Aquarium Air Pump: How It Works and Why You Might Need One

Jennifer Doll

Jennifer Doll


aquarium air pump

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At any given pet shop, you may have heard the bubbling of air pumps coming from the aquarium section. These machines are some of the simplest yet most effective pieces of aquarium equipment that you can get for your fish tank and are highly affordable, too! There are a few different reasons why you might need an aquarium air pump, so we will help you figure out if you should get one and the size and placement that will work best for your aquarium as well.

Keep reading to find out how aquarium air pumps work, why you might need one, and the best product right for your own aquarium.

How aquarium air pumps work

Aquarium air pumps are mechanical pieces of equipment that pull atmospheric air into and down airline tubing, which is then passed across an air stone. The atmospheric air is then released as bubbles into the aquarium water. Simply put, atmospheric air is being directly dispersed into the aquarium water to increase the availability of breathable dissolved oxygen for fish and other aquatic life.

However, fish cannot breathe atmospheric air and rely on dissolved oxygen available in the water column to breathe. As the atmospheric air bubbles rise in the aquarium, water is being displaced and agitated, allowing some of that air to be transferred into dissolved oxygen; carbon dioxide and other gases are also being displaced in the water column and are forced to rise with the bubbles and out of the aquarium. The bubbles create disruption at the surface of the water, further increasing the gas exchange between atmospheric air and the water column in your aquarium.

Aquarium air pumps also help even out gas exchange within the water column. Since air stones are placed at the bottom of the aquarium, any gases settled in the lower water column are disrupted and either exchanged or dispersed to a new area in the tank.

While most air pumps come with everything you need to get started, there are a few additional options you have for the best safety and customizability. Some other supplies you may need for your aquarium air pumps are:

Airline tubing. This tubing is usually clear and plastic. It is used to connect the air pump to the air stones or bubble bars inside your aquarium. Most tubing comes in a standard size, but just make sure that the diameter matches that listed for your air pump.

Check valve. It is always best to use check valves when attaching air pumps to your aquarium. These valves keep the water moving in one direction down the airline tubing, preventing a backward siphon from happening; this is when suction pulls the water back down the tubing and into the air pump. This has a rare chance of happening if the air pump is placed below the aquarium, but is easily preventable by using an inexpensive check valve.

Gang valve. If your aquarium air pump does not have more than one available outlet for airline tubing, then a gang valve will allow for more connections if needed.

Connectors. Other connectors will further customize and monitor the functions of your aquarium air pumps.

Aquarium Air Pump

Why you might need an aquarium air pump

Aquarium air pumps are very handy to have on hand and are the best option to save a tank in the midst of a power outage or other mechanical failure. Here are some reasons why adding an aquarium air pump to your tank might be a good idea:

Aeration. As discussed, air pumps are used to help introduce more atmospheric oxygen into the tank than that would normally enter the system. Air pumps are one of the best options for keeping a tank aerated for species that may not like a lot of flow but that still need decent water circulation.

In most scenarios, air enters the aquarium water through surface agitation either caused by a filter or a powerhead. However, if the species kept inside the tank can’t handle a strong current, then an air pump will achieve the same results. Aquarium air pumps are also favorable if the tank is especially small and other sources of surface agitation are overwhelming in strength and size. They are also very appropriate for paludariums for animals such as frogs and crabs where filtration is a little more specialized.

Note: This is also why it’s less common to see air pumps in saltwater systems as opposed to freshwater; all saltwater life requires a considerable amount of flow, so appropriate powerheads and gas exchange are needed more than what air pumps can offer.

You will find that many hobbyists have extra battery-operated air pumps on hand at any given moment. This is because they are one of the best solutions to save an aquarium during a power outage. When the power goes out, all filtration and water movement stops, leaving little to no gas exchange happening in your tank. This can quickly and sadly lead to your fish drowning due to a lack of dissolved oxygen being present in the aquarium.

A battery-operated air pump gives at least a day for the power to return or for other arrangements to be made. During a tropical storm, I was able to sustain my tank for about 4 or 5 days with a battery-operated pump alone.

Filtration. Another big use of air pumps is for filtration; one of the most common examples is a sponge filter. These filters use air to create pressure that then draws water in through the submerged sponge, filtering out any particles that are brought in with it. A sponge filter is usually used for more delicate species that can easily be sucked into a traditional filter otherwise, like shrimp or the infamous neon tetra.

A sponge filter especially works well for breeding tanks with small fry and quarantine/hospital tanks.

Decoration. Some hobbyists choose to add an air pump to their aquarium simply for aesthetic! Some fish may even like to play in the bubbles and swim in the current, especially certain puffer species.

A backdrop of bubbles brings excitement to the tank while adding beneficial aeration for a reasonable price. When it comes to air pumps, there are two main connective products to choose from: an air stone or a bubble curtain/wall. Both do the same thing and efficiently introduce air into the aquarium, it is simply a matter of visual preference!

One of the most popular aquarium decorations that use an air pump is the typical opening and closing treasure chest. Just make sure that whatever ‘aquarium safe’ decoration that you end up buying is actually 100% aquarium safe! If you don’t like the visual effects that air pumps have in your tank but still want all the benefits that come with using them, you can always set your air pump up to a timer to when the light is not on.

Is an air pump necessary for your aquarium?

Air pumps aren’t necessary for any aquarium, but there doesn’t seem to be any downsides to adding them either as long as the tank isn’t densely planted. Some products can be a little noisy, but usually, they just need to be ‘broken in,’ placed on a soft mat, or are low quality. Otherwise, they can serve as a means for aeration, filtration, and decoration.

However, in a planted tank, plants will need carbon dioxide to undergo photosynthesis. Air pumps are usually too efficient at removing that carbon dioxide to be used correctly in a planted aquarium. If there is a lack of carbon dioxide, then plants will not be able to grow and their overall health will suffer. Air pumps will also counteract most of the CO2 that you manually inject as well.

Aquarium placement & size

There are a few things to keep in mind before going to purchase your aquarium air pump:

  • Where does the air pump go in a fish tank?
  • How big of an air pump does your aquarium need?
  • Do you want an air stone or a bubble curtain/wall for your aquarium?
  • Where does the air pump go in a fish tank?
  • What is the best aquarium pump for you?

Where does the air pump go in a fish tank?

While these products tend to be small, they do need to be placed on an even flat surface. This means that there needs to be ample space around or underneath the aquarium to keep the pump. Also, keep in mind that air pumps will require additional power outlets.

Though typical air pumps include all the accessories needed for quick installation, it is possible that the airline tubing that is included is too short to reach your desired placement. Some air pumps also tend to rattle and vibrate even when placed on a flat surface, so other additional accessories needed may be a piece of foam or other silencing barriers.

Space will also need to be considered for any additional air pumps used.

Note: Always remember to allow for a drip loop with all aquarium electronics.

How big of an air pump does your aquarium need?

Aquarium air pumps are rated by gallons just like most filters. It is recommended to get an air pump that is slightly larger than what is suggested, so if you have a 55 gallon (208.2 L) aquarium, it may best to go with a pump rated for 75 gallons (283.9 L). This is to avoid getting an air pump that doesn’t push as much air as your aquarium might need; keep in mind that in order for these products to work as they should, they need enough power to create some turbulence in the tank that reaches the surface.

If you have a larger tank, it may be best to get two or more air pumps if you’re using them to oxygenate your tank. Some air pump products have more than one area to attach an airline tubing, allowing you to have multiple air stones coming from the same pump. In this case, it would definitely be best to go with products rated for larger tanks.

Do you want an air stone or a bubble curtain/wall for your aquarium?

If you’re looking to get an air stone, your aquarium air pump doesn’t have to be as powerful as one that would fuel a bubble curtain/wall as the air is being forced in one concentrated area; if the air pump is too weak, then the farthest part of the bubble bar may not reach its maximum output. Stronger pumps will also make for a more impressive backdrop!

Remember, both types of air pumps work in the same way to aerate the water. It is entirely up to personal preference which one you think looks best in your home aquarium.

Where does the air stone or bubble curtain/wall go in the fish tank?

Both air stones and bubble curtains/walls should be placed towards the bottom of the tank so that they sit just above the substrate. This will result in the best gas exchange, allowing gases from the bottom of the tank to rise to the top and be replaced with new atmospheric air.

Air stones and bubble curtains/walls do have a tendency to mysteriously float to the top. They will need to be anchored down, usually be rocks or plant clips. Most hobbyists like to keep their air stones in the corners of their tank, as you are limited by the length and practicality of your airline tubing. Bubble curtains/walls usually look best when centered in the middle of the tank; it will probably need to be suction-cupped onto the glass.

There isn’t too much to worry about if either becomes unsecured; fish know to get out of the way for the most part. The only concern is if the air pump was acting as your main filter and source of oxygenation. It would be best to make sure that the pieces are tightly secured.

What is the best aquarium air pump for you?

The ideal aquarium air pump will be correctly rated for your aquarium size, quiet, and long-lasting. Luckily, they are usually cheap in price and will last at least a couple of years. If you’re looking for something even more longterm than that, it may be worthwhile to look at higher-end models, but in the end, they all help to aerate your aquarium to make more dissolved oxygen available for your fish.


Aquarium air pumps are a cheap investment that can be used to aerate a display tank or a hospital/quarantine tank to increase the amount of dissolved oxygen available for your fish to breathe while exporting carbon dioxide. Bubble curtains/walls make an especially appealing backdrop that works best when secured in place. Also, keep in mind to allow enough space for the air pump to either sit next to or underneath the aquarium.

If you have any questions about aquarium air pumps, or you have experience with a personal favorite aquarium brand of air pumps, don’t hesitate to leave a comment below!

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