What Does an Air Pump Do in an Aquarium? (Explained)

what does an air pump do in an aquarium

“What does an air pump do in an aquarium?” is a question that might sound silly to seasoned aquarists. However, it is a valid query for beginner aquarium hobbyists who might be clueless about the roles and functions of some fish tank accessories.

The short answer to this question is supplying the fish tank with supplemental aeration, promoting circulation, and encouraging efficient gas exchange.

Please continue reading to learn the nitty-gritty of an air pump for fish tank units.

What is an Air Pump in Fish Tank?


Let us start by appreciating the aquarium air pump definition. To put it simply, an air pump is an electronic device that forces “air” through a tube or similar structure.

It is similar to a water pump, except it pushes “air” out from its port instead of water. The device connects to various fish tank accessories, such as sponge filters, air stones, breeder boxes, egg tumblers, and moving bed filters.

What Types Should I Know?


Fish tank air pumps come in two types, battery-operated or electric.

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  • Battery-powered air pumps are perfect for aquarists concerned about electrical safety. Water splashes from the aquarium should only damage the air pump battery power unit, not the household electrical outlet.

Unfortunately, battery-powered air pumps do not last long. Although they might feature rechargeable batteries, a lithium unit has a limited lifespan of two to three years. The good news is you can always get a battery replacement.

  • Electric versions ensure round-the-clock air pump operation. You could place air pump in fish tank units without worrying about draining the battery. Your only concern is during a power outage. Electrical safety is also paramount.


What is the Purpose of an Air Pump?


An aquarium air pump purpose varies across aquarists and aquarium setups.

You can optimize an air pump’s function by connecting it to an appropriate fish tank accessory. If you read the air pump instructions, you might notice you can connect it to an air stone, sponge filter, or even a corner box filter.

  • Air stones are perfect for muffling the air pump’s noise, allowing you to sleep soundly at night. These accessories can also improve fish tank filtration and keep the water fish-friendly.
  • On the other hand, connecting the air pump to a sponge filter, corner box filter, or under-gravel filtration unit can improve the removal of dissolved organic compounds, debris, and other particles. It ensures a safe watery environment for your aquatic friends.

Below are the most common purposes for using an air pump:

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  • Increase oxygen levels

Fish tank air pumps increase oxygen levels in the aquarium and facilitate carbon dioxide removal. The action gives more “breathable” oxygen to fish and other livestock.

  • Aerate fish eggs

Fish breeders love air pumps to aerate fish eggs, agitating them gently to improve egg viability and reduce fungal growth. Breeding fish also requires adequate oxygenation, a purpose that air pumps provide efficiently.

  • Maintain water quality

Biological filters can also connect to an air pump, allowing beneficial bacteria to grow and multiply. This action enables the fish tank to maintain its ideal water quality parameters.

  • Decorate the tank

And if you have aquarium decorations (i.e., sunken treasure chest) requiring “live action,” an air pump can help.


How Does it Work?


We have been talking about what an aquarium air pump is and its purpose (or purposes). But the real question remains, how does air pump work?

The air pump sucks oxygen-rich air and forces it into the water, forming air pockets or air bubbles as it hits the water. Fish “breathe” these tiny air pockets in the water without surfacing, allowing them to stay underwater.

Because air is lighter than water, air bubbles rise to the surface. As the air bubble loses contact with water, it pops. The good news about air bubbles breaking at the water’s surface is they release carbon dioxide into the atmosphere.

Air bubbles rising to the surface also agitate the water, further improving gas exchange between carbon dioxide and oxygen.

So, that is how an air pump work in aquarium units.

Benefits of an Air Pump


We know air pumps are essential tools for improving oxygenation in aquariums. We also understand how they work. You might wonder what are the benefits of air pump in aquarium units. Here they are.

1. Ensures ideal oxygen levels for fish and livestock

Fish need five to seven parts of oxygen for every million parts of water (ppm) to lead healthy lives. If the oxygen level drops to two ppm or less, the fish is at risk of oxygen deprivation. Meanwhile, too much oxygen can result in lethal gas bubble disease, which can be fatal.

The good news is air pumps have modifiable air outputs. You can dial in the correct setting, but only after measuring the fish tank’s oxygen levels with an oximeter. Note that the ideal oxygen level for most aquariums is 1 gallon per hour per gallon of fish tank water.

2. Improves gas exchange

Agitating the water surface promotes an effective exchange between oxygen and carbon dioxide.

Oxygen cannot pass through the water’s surface layer without the air bubbles breaking the surface tension. Meanwhile, carbon dioxide cannot escape the water without the air pockets bursting their bubbles at the surface.

High CO2 levels prevent fish from effectively transporting oxygen in the blood to different tissues. They become sluggish, swim toward the surface, and have delayed feeding reactions. Too much carbon dioxide in aquarium water can also lead to suffocation.

3. Facilitates efficient treatment of “sick” fish

We do not put “sick” fish to live with “healthy” species in the same aquarium. That is why we always have a quarantine tank to accommodate “ill” fish and promote faster recovery while preventing cross-contamination.

One treatment method for fish with suspected infections is increased water temperature. Unfortunately, warming the fish’s aquatic environment reduces oxygen levels.

An air pump can introduce oxygen into the warm water, allowing the fish to recuperate from its illness faster.

4. Promotes more effective filtration

Many aquarium filters require an air pump to improve their filtration capabilities. Examples of filters that need an air pump to work effectively include sponge filters, under gravel filters, and corner or box filters.

Box filters are perfect for small aquariums, enhancing biological filtration and aeration when connected to an air pump. It is the same story with sponge filters, relying on air to promote beneficial bacterial growth.

We can expect a similar effect with under gravel filters, ensuring a safe watery environment for your fish.

4. Improves fish tank aesthetics

Bubbles rising to the aquarium’s water surface are a joy to behold. They mimic underwater adventures, such as scuba diving, snorkeling, and other activities.

Connecting an air pump tubing to treasure chests, underwater volcanoes, and toy scuba divers can create an underwater world so mesmerizing it will have guests talking about the fish tank for hours.

Ways to Properly Aerate a Fish Tank


Although an aquarium air pump work to aerate the fish tank, it is not the only method available for aquarists. Here are some tricks to help you properly aerate your fish tank without an air pump.

1. Use a high-flow aquarium filtration system.

A waterfall-type filter, power filter, or spray bar can agitate the aquarium water and introduce oxygen without an air pump. However, you might want to be cautious when using these devices because the high-flow design might make life more miserable for your fish.

2. Add live aquatic plants.


Plants need carbon dioxide to produce food (via photosynthesis) and give off oxygen. Hence, the more plants you have in the aquarium, the more oxygen the aquarium has for your fish.

You can add the fast-growing Hornwort or the low-maintenance Eelgrass. Ludwigia repens and Anacharis are other plant species worth putting into the aquarium to improve oxygenation without an air pump.

3. Perform the cup method.


Here is an old-school method that can aerate the fish tank without an air pump. Get an empty cup and scoop water from the aquarium. Raise the cup as high as possible and slowly pour the water into the fish tank.

Frequently Asked Questions


How long should you run an air pump in a fish tank?

Some folks recommend operating an air pump six to eight hours daily, while others say it is okay to use an air pump continuously 24/7 to ensure adequate aquarium water oxygenation.

You can turn off the air pump at night if you cannot sleep because of the device’s noise.

Should you leave air pump on all time in fish tank?

Leaving the air pump on all the time in the fish tank is acceptable, provided you can sleep with the buzzing sound at night. We advise you to turn off the air pump if the water temperature increases more than what is comfortable for fish.

A fish tank oxygen pump improves aquarium water circulation and oxygenation, allowing fish tank inhabitants to live healthier and more robust lives. Leaving this gadget on all the time guarantees happier fish.


What does an air pump do in an aquarium? By now, you should be able to provide a comprehensive answer regarding this topic. To jog your memory, its main purpose is introducing more oxygen into the fish tank.

Adding oxygen to aquarium water promotes more effective biological filtration, ensuring a safer environment for fish and livestock. It can also promote a healing ecosystem for sick and quarantined fish while improving overall aesthetics.