Properly Aerating Your Aquarium - (2023)

Learn the basics of aeration and how to properly aerate your aquarium.

Fish can be found in a variety of environments all over the world -- live in oceans, lakes, ponds, and rivers. These bodies of water all have large surface areas and often strong current which keep the water moving. Water movement and circulation serves to oxygenate the water so that fish have the air they need to breathe and survive. However, in an aquarium, the surface of the water is greatly reduced. Therefore, artificial ways of oxygenating the water must be accomplished through aeration. There are several ways to aerate your aquarium and these methods will be discussed in this article.

Before discussing specific methods, it is important to address the surface area of the water in your aquarium. The greater this surface area is, the more water that is in contact with the air at any given moment. This leads to greater oxygen absorption by the water. Therefore, you should try to maximize the surface area in your aquarium. This issue is particularly important to consider when you are thinking about the shape of a tank – standard tanks are rectangular with a greater width than height but some tanks come in “tall” sizes with walls that are taller than they are wide. Many people mistakenly assume that you can keep the same number of fish in a 20-gallon standard tank as you can in a 20-gallon tall tank. However, the 20-gallon standard tank actually has a larger surface area due to its length and width dimensions. You need to be careful with tall tanks or irregularly-shaped tanks (such as hexagons), as the water surface can be fairly small. This smaller surface limits the stocking capacity of the aquarium.

Oxygen/Carbon Dioxide Exchange Basics

As your fish breathe, they absorb oxygen from the tank water and their bodies convert it into carbon dioxide which is then exhaled. Oxygen and carbon dioxide are also exchanged at the water’s surface -- carbon dioxide is released from the water into the air. This is important because your fish would die if the CO2was never allowed to escape into the atmosphere – it would simply build up in the tank, causing your fish to slowly suffocate.

While CO2is being released from the water into the air, oxygen is also being absorbed from the air into the water. This is important because it increased the oxygen content of your tank water, providing the oxygen your fish need to breathe. For this gas exchange to occur, however, the surface tension of the water must be broken – this allows for carbon dioxide molecules to be released and oxygen to be absorbed. Agitating the surface breaks this surface tension and allows for a proper exchange of gases.

Temperature and Oxygen Concentration

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As the temperature of your aquarium increases, the oxygen content in it decreases because the evaporation rate of your tank water will be higher. Therefore, the higher you keep your tank’s temperature, the more aware you need to be of whether or not your fish are getting enough oxygen. Once you get above 800F, you will probably have to provide some of the aeration devices listed below in addition to your filter.


For many aquariums, a simple HOB (hang on back) filter will adequately aerate your tank. Many filters have outputs that drop the water into the surface of the tank and, therefore, provide adequate surface agitation. This surface disturbance increases the surface area in contact with the atmosphere and, therefore, increases oxygen absorption. Additionally, the filter circulates the water in your tank which is important because it moves the water at the bottom of your aquarium (water that is not gaining oxygen from the air) to the top surface so it can increase its oxygen concentration.

Pros/Cons of Filters

- helps to increase aeration/oxygen content
- increases circulation of tank water and thus surface area
- rotates tank water from bottom of the tank up

- may create dead spots depending on filter placement

Power Heads

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If your filter is not disturbing the surface enough or providing enough circulation, you can use a power head as well. A power head siphons water up out of the tank and mixes it with air as it is expelled. Many power heads also let you adjust how much air they intake which enables you to adjust how many bubbles are produced (see the paragraph on air stones below to see how bubbles help in aeration).

Power heads can also be useful in eliminating dead spots in the tank – areas where water circulation is particularly low. A carefully placed power head can serve to increase the circulation in these areas of your tank. Filters, air stones, and decorations often do not adequately aerate large aquariums. Therefore, power heads are often the preferred method for larger tanks. However, you can easily provide too much current in small to medium sized aquarium with power heads, so be sure to buy one rated for smaller tanks or buy one that has an adjustable flow rate.

Pros/Cons of Power Heads

- makes a great supplemental source of aeration
- can help to deal with dead spots in the tank
- may increase overall aeration

Air stones

An air stone is a porous stone that is connected to an air pump to produce bubbles in an aquarium. Many think these pumps are too noisy and, therefore, choose not to use air stones. However, placing the pump on a sponge will usually dampen the noise significantly. Some hobbyists really like the look of a bubble wall in their aquarium and, therefore, use them even when further aeration is not needed. It is not actually the bubbles that provide the oxygen to the water (a common misconception), but it is their disturbance of the surface and ability to provide more water circulation that helps to raise the concentration of oxygen in the tank.

Pros/Cons of Air Stones

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- can be installed in virtually any tank
- adjustable flow rate, ideal for any size tank
- helps to increase surface agitation and circulation

Aerating Ornaments

Who doesn’t like a nice pirate ship that moves back and forth while simultaneously producing bubbles? How about a nice treasure chest? Or a fake shell? If you don’t like the natural look, but instead love putting these kinds of decorations in your aquarium, they can serve the same purpose as an air stone but with a little more flair.

Pros/Cons of Aerating Ornaments

- can enhance the appearance of your tank
- may increase aeration in the tank
- might take away from the “natural” appearance of a tank

How to Tell if Your Fish do not Have Enough Oxygen

It is sometimes difficult to tell whether you are giving your fish enough oxygen because they might not show any symptoms at first. The most telling sign that your fish need more oxygen is if you see them gasping at the surface -- they will also tend to hang out back by the filter output. This area of your tank tends to possess the highest oxygen concentration as it is near the most disturbed surface. Another indicator is if you see bottom-dwelling fish constantly having to go to the upper part of the aquarium. If you see any of these indicators, use one of the methods described above to provide more oxygen to your fish.

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How to Tell if You Have Too Much Circulation

While not having enough oxygen in the tank is the more common problem, you can also provide too much circulation in your aquarium. Obviously, if you see your fish being whisked around the aquarium or see them greatly struggling, you need to reduce the amount of circulation. Different species will be able to handle more water movement than others. Some fish (such as bettas, for example) prefer very still water so a small amount of current may be too much for them. Others actually prefer strong currents to play in. Research your specific fish and observe their behavior to see what they like.

Other Tips for Oxygen Concentration

Adding some sort of aeration device to your tank is not the only way to increase its oxygen content. Another simple way to up the oxygen concentration in your water is to add live plants to your tank. Like aquarium fish, plants go through the process of cellular respiration, converting carbon dioxide into oxygen that is available for breathing. An interesting fact about having live plants in your tank is that while your fish may die from lack of oxygen, your plants could die from lack of carbon dioxide. This makes live plants and aquarium fish the perfect duo – they provide what the other needs to survive.

Having live plants in your tank while providing adequate circulation and aeration for your fish can be tricky. Aquarium plants tend to do best in tanks with low water flow because they may be uprooted by water that moves too quickly. To deal with this problem, make sure your plants aren’t situated directly beneath the release flow of your filter and place them away from other aeration devices. You should also avoid placing plants too near your water heater because it could damage them.


While many factors play a role in keeping your fish healthy, aeration is one of the most important. Properly aerating your aquarium allows your fish to breathe properly, which is essential for good health. The devices most commonly used to increase aeration in fish tanks are filters, power heads, air stones, and aerating decorations. Use whatever combination you like to provide your fish with the oxygen they require.

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How much aeration does a fish tank need? ›

Generally, an appropriate amount of air in a tank is around 1 gallon per hour for every gallon of water in your tank. Air pumps have adjustable outputs, so setting a desired air output is simple.

Can a fish tank have too much aeration? ›

Too much oxygen in water can lead to the potentially lethal gas bubble disease, in which gas comes out of solution inside the fish, creating bubbles in its skin and around its eyes. (Excess nitrogen, however, is a far more common cause of this disease.)

What is the best way to aerate a fish tank? ›

The devices most commonly used to increase aeration in fish tanks are filters, power heads, air stones, and aerating decorations. Use whatever combination you like to provide your fish with the oxygen they require.

How do I know if my fish tank has enough oxygen? ›

Aside from actually testing the water for dissolved oxygen, the only indication of trouble will be the behavior of your fish.
  1. Fish will initially react to lower oxygen levels by moving around less. They will swim less vigorously and even eat less often. ...
  2. Eventually, fish will begin gasping at the surface of the water.
May 4, 2022

Does a fish tank air pump need to be on all the time? ›

Generally speaking, you should leave the air pump on all the time to help your fish get good water circulation and plenty of oxygen to breathe.

How do you calculate an aeration tank? ›

A reliable procedure used to calculate the oxygen required is given step wise as:
  1. ETP Capacity in m3/day.
  2. Inlet BOD in mg/l.
  3. Desired Outlet BOD in mg/l.
  4. Total BOD to be removed (Influent) = inlet BOD 8* ETP capacity in kg/Day.
  5. Hence O2 to be transferred in kg/Day.
  6. Method of Aeration = Fine Bubble Diffuser.

Do bubblers stress fish? ›

Certain fish have adapted to stagnant water, like betta, and can even draw water from the surface. In this case, the water movement caused by a bubbler can actually stress the fish.

Does aeration help with algae in aquarium? ›

Improving other Algae Treatments

Aeration can protect your pond and your fish during an algae bloom and die off. Adding an aeration device will provide added oxygen to the water and help buffer the effect of an algae die off, either naturally or when the algae is treated by some other means.

Does aeration raise pH in aquarium? ›

Aeration – Increasing the oxygen concentration in your water will serve to drive down the carbon dioxide concentration. As discussed above, less carbon dioxide translates to a higher pH. Therefore, you can increase the aeration in the tank to raise the pH.

Can a bubbler be too strong? ›

An air pump that is too powerful can wreak havoc in your aquarium. When attached to a sponge filter, it can cause a current strong enough to stress fish that prefer calm water. Or, maybe it's causing your airstone to work overtime, producing so many bubbles that you can't see your fish.

How long can a fish tank go without aeration? ›

An aquarium fish can stay up to two days without oxygen (in still water) but they still need some more amount of oxygen to breathe and do their essential daily work.

What depletes oxygen in fish tank? ›

The primary cause of oxygen depletion in a water body is from excessive algae and phytoplankton growth driven by high levels of phosphorus and nitrogen. During the nighttime hours, these photosynthetic organisms consume oxygen through respiration when engaging in active photosynthesis.

What level of oxygen do fish need to survive? ›

Warm-water fish usually survive at dissolved-oxygen concentrations as low as 1.0 m/L, while cold-water fish normally survive at 2.5 to 3.5 mg/L dissolved oxygen. However, fish and other aquatic animals are stressed, susceptible to diseases and grow slowly at low dissolved-oxygen concentrations.

What is a good oxygen level for fish? ›

The favorable dissolved oxygen level for fish culture is between 5 and 20 ppm. 1. Oxygen production by aquatic plants decreases when there is not enough sunlight due to cloudy weather. 2.

How long should I run my fish tank air pump? ›

How long should you run an air pump in a fish tank? First, do not run an air stone when you are adding CO2. Secondly, you can run the air pump 24/7 or you can put it on a timer and only let it run during either day or night time. I would suggest running it on a timer for just as long as you are keeping your light on.

Do I need a filter if I have an air pump? ›

They are Required For Sponge Filters

Sponge filters will only work with an air pump because they don't have a motor of their own so they rely on the upwards thrust of an air pump to drive the water from the tank through the sponge filters.

How much aeration is too much? ›

Too much is not good

Most wastewater treatment plants operate their aeration zones and aerobic digesters at 1-3 mg/L dissolved oxygen (DO). Anything more may waste DO and energy. Even aerating at 1 or 2 mg/L over the DO setpoint can be extremely wasteful. Over-aeration can also cause operational problems.

What is the rate of aeration? ›

The broadly quoted aeration rate used in a typical fermentation is one volume of air per volume of medium per minute. Thus, a 100 m3 antibiotic fermentation may need up to 100 m3 of sterile air per minute.

What is the formula for aeration period? ›

The aeration period is the detention time of the raw-wastewater flow in the aeration tank expressed in hours. It is calculated by dividing the tank volume by the daily average flow without regard to return sludge.

Why is my fish swimming in the air bubbles? ›

Fish need oxygen to survive. If your tank is loaded with toxic chemicals, like chlorine and ammonia, the fish get their own oxygen by floating to the surface and blowing bubbles. This is a sign that your fish are in danger.

How do you tell if a fish is stressed? ›

If your fish is swimming frantically without going anywhere, crashing at the bottom of his tank, rubbing himself on gravel or rocks, or locking his fins at his side, he may be experiencing significant stress. Talk to your veterinarian about treatment and look into what may be causing the stress and alleviating it.

Does tapping glass stress fish? ›

The same noise level in the air could lead to serious hearing damage over time. And fish have it even worse: since the sound pressure is four times higher under water than it is in the air, a good portion of deaths in public aquarium can be traced back to repeated tapping on the glass.

Does aeration make water clear? ›

Aeration is all about gasses. Aeration mixes the pond so toxic gasses are efficiently released and life-giving oxygen readily replaces it. An aerated pond will be clearer, cleaner, and have less bottom muck than a pond without aeration.

Does aeration reduce ammonia in fish tank? ›

By increasing the aeration of your tank's water, it might help diffuse that ammonia gas out of the water and into the air. Aeration won't do much in a large pond, but it might help manage ammonia levels in your fish tank. You can buy an aeration pump at most pet stores or online.

What temperature kills blue green algae? ›

When incubated in the light under 100% oxygen, wild-type blue-green algae (Anacystis nidulans, Synechococcus cedrorum) die out rapidly at temperatures of 4 to 15 C, and at 35 C (or at 26 C in the case of S. cedrorum) in the absence of CO(2). Photosynthesis is impaired in these cells long before they die.

Should you turn off bubbler at night? ›

Generally you should leave the air running all the time. The bubbles create surface agitation which helps keep your water oxygenated and at nice stable equilibrium with the ambient air. They also improve water circulation in the tank. There is no benefit to the tank in turning off the air.

What should the pH of water with aeration be? ›

The pH of the aeration tank should be between 6.5-8.5 to avoid stress on the microbial community and for optimal biological activity. Dissolved oxygen levels in the aeration tank must be maintained at 1-3 mg/L for effective treatment.

What does aeration do to fish? ›

Supplemental aeration will not only help maintain the plants during this time, but also provide adequate oxygen so fish do not suffer as a consequence. Aeration also will buffer your fish from rapid drops in oxygen due to large plant or algae die offs.

Do you need an aerator in a 10 gallon fish tank? ›

No it is not needed, but it is one way. In still water oxygen takes about six months to move down 1 meter! So you need something, Any device (for instance a pump or bubble tube method) which moves water from the bottom to the top will do.

Can too much aeration cause algae? ›

When you have too much decomposing waste in your pond, the natural oxygen levels can drop significantly, causing nitrogen and phosphate levels to rise. This increase in nutrients results in aggressive algal blooms.

How many passes should I make when aerating? ›

For highly compacted soil or soil that hasn't been aerated in more than a year, make two passes with the aerator: one following your mowing pattern, and the second at an angle to the first. Aim to create 20 to 40 holes per square foot.

What happens if you over aerate? ›

If it's exposed to too much air, the wine will taste old and nutty, without much personality. Eventually, it will even turn into vinegar. However, exposing wine to the right amount of oxygen can make it seem more expressive, smoother, and enjoyable.

How often should I water after aeration? ›

During the first two weeks following your aeration and seeding service, the main goal is to keep the ground/seed moist while the seed begins to germinate. We recommend that you water each day for at least 20 minutes in all areas of the lawn (water the soil to a depth of about 1/4”).

Do fish like air bubbles? ›

Some Fish Like Bubbles More Than Others

Schooling fish aren't afraid of bubbles, but they avoid them if they think it may disrupt their coordinated swimming.

How long will a UPS run a fish tank? ›

Assuming a rudimentary 70-gallon fish tank uses 100 to 150 watts of electricity, the SU1000XLA fish tank UPS should keep your aquarium creatures safe through most short-term power outages. It will support a load of 200W for 31 minutes, and your connected equipment likely carry a smaller load than that.

Do fish like air stones? ›

It does this by releasing tiny bubbles of air into the water, which increases oxygen levels and circulation. Air stones are an important part of any aquarium, as they help keep your fish healthy and happy. They are especially beneficial in smaller tanks, where oxygen levels can drop quickly.

Are big air bubbles good for fish tank? ›

The answer is an absolute yes, it does not matter whether you have a filter in your aquarium or not, attaching an air stone makes the water circulation much better. Adding an air stone will keep the water cleaner, provide the fish with more oxygen, and it has a lot of health benefits for the aquatic life.

Do bubblers put oxygen in water? ›

Aerate the water

To do this, fish draw dissolved oxygen out of the water – without it, most breeds of fish will suffocate. Bubblers add oxygen to your aquarium.

Can you manually aerate a fish tank? ›

You can add oxygen to your tank by slowly pouring water into it from some height above. The water will pick up air en route as well as drive oxygen into the tank water. How much oxygen is added depends on how high above the tank you pour the water and how many times you repeat this procedure.

Is it OK to water after aeration? ›

Begin watering immediately after the aeration work is complete. Light and frequent watering is preferred for seedlings. Dos Amigos Landscaping recommends watering to the point where at least 1 inch of the top of the turf is wet or light puddling is taking place. Water at least two times per day.

Does aeration lower or raise pH? ›

AERATION! When water is aerated, it creates turbulence. The turbulence then causes the aqueous CO2 (carbon dioxide) to outgas. Outgassing of CO2 from water results in an increase in pH.

Does aeration improve water clarity? ›

Enhance Water Quality with Aeration

Water quality is also greatly improved through the use of aeration. Under oxygen-deprived or anoxic conditions, lake-bottom sediments release various gases and metals that can cause water quality problems.


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