How to Aerate Aquarium Water (3 Simple Solutions)

Aerating an aquarium is necessary because still water tends to have very low oxygen levels. The surface of the water creates a barrier that prevents CO2 from escaping and stops oxygen from being replenished.

Breaking the surface of the water with bubbles or circulating water encourages gas exchange at the surface and helps to move the oxygen around the entire aquarium.

Here are three simple ways you can aerate your aquarium water.

Just remember, an aquarium needs more than just simple aeration for fish to thrive. Filters also provide mechanical and biological filtration that is essential for a healthy tank. If you’re not familiar with the Aquarium Nitrogen Cycle, please, see our in-depth article, here.

1. Filters

Filters provide a good amount of aeration in an aquarium as they circulate water throughout the tank. Keeping the water moving helps break up the surface tension, allowing for gas exchange at the top of the tank.

Some kinds of filters are better at aerating the water than others. A powerful canister filter will likely provide all of the aeration that you need in a tank. But, a small internal filter can only provide aeration in a small area.

If you’re wanting to increase the aeration and filtration in your tank, adding on a small, air-driven sponge filter is a great solution. The bubbles will aerate the water and the sponge will provide mechanical and biological filtration. Please, see our detailed sponge filter article, here.

2. Air Pumps

Air pumps are a really simple way to aerate a tank. Air pumps sit outside the aquarium and pump air through vinyl airline tubing into the water.

At the end of the airline is a diffuser of some kind, usually an airstone, that breaks the air stream into a mist of super fine bubbles.

As the bubbles rise to the surface, they drag water along with them, increasing water circulation. The stream of bubbles breaking through the water’s surface causes even more gas exchange.

I especially like to put an air pump on the opposite end of the tank from the filter. This helps make sure that there are no dead zones in the aquarium, areas where there is no circulation, and therefore much less oxygen.

Plus, the stream of bubbles rushing to the surface is really pleasing to look at.

I prefer to use air pumps in tanks with fish that don’t do well with strong current, like angelfish, Bettas or fancy guppies. The stream of bubbles adds on lots of aeration, but doesn’t create an overly strong current these species would have to fight against.

Please, see our in-depth comparison of air pumps, here.

3. Powerheads 

Powerheads are submersible water pumps that are placed inside the aquarium to provide additional water circulation.

Placed near the surface of the water, they can help break up surface tension, increase gas exchange, and push oxygenated water around the aquarium. 

Powerheads for freshwater tanks are pretty simple to operate, you simply stick them to the glass and plug them in. 

I especially like to use powerheads in tanks with fish that originate from fast-moving rivers or streams.

Fish like loaches, white cloud mountain minnows or zebra danios all appreciate a strong current in the tank. 

Please, see our in-depth comparison of powerheads, here.

Final Thoughts

Aquarium aeration is highly important. Fish use up oxygen and excrete CO2, and without proper aeration, there will not be enough gas exchange in the tank to keep a healthy balance.

Luckily, there are lots of options out there for aerating a fish tank.

Filters are the first line of defense when it comes to circulating water in the tank. They move water around and help to detoxify waste byproducts that are dangerous to fish.

Air pumps and powerheads are a great way to add on even more aeration. Air pumps are better for fish that don’t like a lot of current, while powerheads are the better choice for fish that are strong swimmers and enjoy a lot of current.

I hope you find this article helpful.

I wish you and your fish the very best!

Katherine Morgan
Katherine Morgan

Hey, there! I'm Katherine from Northwest Florida. An aquarium specialist, I've kept tanks for over two decades, enjoy experimenting with low-tech planted setups and an avid South American cichlid enthusiast.

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