Air Pump vs Filter vs Powerhead: 3 Reasons You Want an Air Pump

In Aquarium Filtersby PaulK


The function of an air pump is to pump air from the atmosphere into your aquarium. Using an air pump with an airstone creates bubbles that float to the surface and create surface agitation that allows for the exchange of gases allowing oxygen from the air to enter the water for your fish. The fish absorb the oxygen through their gills.

Getting an air pump for your fish tank is not an absolute necessity, but they are inexpensive and nice to have in your aquarium for several reasons.

Reason #1
Air pumps combined with air stones provide lots of surface agitation. Surface agitation creates waves on the surface of your fish tank which allows an oxygen exchange with the air. Oxygen is obviously what your fish need in the water to survive.

Now, if you live in a climate where the ambient temperature doesn’t get too hot, then you don’t need to worry about this too much as the water won’t reach temperatures that reduce oxygen. The hotter the water gets, the less oxygen is present. So if you live in hotter more tropical areas, you will want to consider using an air pump.

You can get this same surface agitation from a cascading hang on the back filter or a wave maker, but the air pump with airstone is an inexpensive way to accomplish this. Not that you won’t need a filter mind you, but air pumps are a good addition to any fish tank.

Reason #2
Air pumps are good for water movement. Water movement or flow is good for any fish tank because you don’t want ‘dead spots’ in your aquarium where detritus can build up. Detritus is extra waste that builds up in areas of your fish tank over time. If that gets to be a problem, it will start to decompose creating ammonia and nitrite. Not healthy for your aquarium. So you want a good water flow that the filter can pick up and clean. Then return that clean water back into your tank.

Another advantage of water flow is to distribute heat throughout the fish tank. It’s better to have an even temperature throughout the fish tank because hot and cold spots could stress the fish.

Reason #3
If you use or are thinking of using a sponge filter or under gravel filter, then you’ll want an air pump. Using a sponge filter is a really inexpensive way to filter your fish tank. Sponge filters can serve a dual purpose by providing the bacteria filtration and provide surface agitation for the oxygen exchange. Undergravel filters are a bit old school, but some people still use these and they work pretty good.

What is an Airstone?

An airstone or aquarium bubbler is a porous stone or glass attachment that goes on the end of your tube running from the air pump into the fish tank. It’s purpose is to produce bubbles which then float to the top of the fish tank creating surface agitation. Glass air stones generally work the best.

They also come in various levels of coarseness that produce fine to large bubbles. The finer the bubbles, the more effective the airstone is at providing surface agitation and water circulation. Finer air stones will, however, clog easier and need to be replaced more often.

Air stones come in varying lengths as well depending on how much flow you want and the look. Long air stones provide a bubble wall that looks cool, but you will need a stronger pump.

Why use an airstone?

The main benefit of using an airstone is to create more water circulation for your filter. The better the water circulation, the cleaner the water. If you already have a pretty decent water flow, then an airstone won’t provide much benefit, but some people like the look of bubbles in the tank and it wouldn’t hurt to give your fish tank every advantage.

Aqueon Quiet Flow 60 Aquarium Air Pump, Up to 60 Gallons

Aqueon QuietFlow. Click photo for pricing info.

Where does an air pump go in an aquarium?
An air pump is going to sit outside of your aquarium somewhere. You then install a tube or tubes that run into the fish tank.

If you set it somewhere lower than the aquarium, you will need to attach a check valve. A check valve prevents water from siphoning back into the air pump if the power goes out. To install that you’ll have to cut the tubing about a foot or two from the air pump intake and use it as a connector to the other portion of the tubing going into your aquarium.

Certain models, like the Aqueon QuietFlow, already have a check valve built in the bottom of the unit, and they’re serviceable, meaning you can replace just that part and not the whole pump.

What size air pump do you need?

The ratings should be on the box when you purchase the air pump. So if you have let’s say a ten-gallon tank the rating on the box should include that size as acceptable. Pretty straightforward.

Keep in mind that these ratings for using a filter in conjunction with the air pump. If you’re just going to run an airstone, then a small, quiet air pump will do the trick.

What are the best air pumps?

Eheim Air Pump 400

Eheim 400. Click photo for pricing info.

The best air pumps are quiet air pumps. The vast majority of air pumps will have a hum that you probably won’t even notice after a while. As you turn it up, the hum will get louder so it depends on the setting. Another factor is the surface you place it on, or if it’s inside a cabinet or not. Air pumps have rubber footings supposedly to absorb some of the rattling. It does help somewhat but is not a big factor.

There are some videos on youtube that review the quietness of some popular brands. The Eheim seems to be the winner on quietness but is also a very expensive option. So if you want to spend the money, the Eheim 400 is the way to go.

Air Pumps vs Powerheads

What the heck is a powerhead?
Think of a powerhead as an air pump that is submerged in your fish tank. Powerheads really serve the same purpose as an air pump airstone set up. Powerheads circulate the water and create surface agitation more effectively and efficiently than air pumps and air stones.

For smaller tanks under 25 gallons, a powerhead is probably overkill. Most freshwater fish are not accustomed to strong currents, so you’ll see powerheads mostly in reef tanks. If you have betta fish that don’t like a lot of current you probably shouldn’t go with a powerhead.

One other benefit of Powerheads is they also keep down the growth of algae. Algae tend to grow in stagnant water and a powerhead or two keeps the water circulating and cleaner. That helps prevent algae from growing.

Fish Tank Air Pump vs Filter

In most cases, your aquarium filter will do an adequate job of water circulation, aeration, and keeping the water clean so you won’t really need an air pump with air stone. Can an air pump replace an aquarium filter? I would say that’s not a good idea because of the biological media that’s necessary to maintain water quality.

Some filters do a better job of water circulation than others. For example, an HOB power filter primarily intakes and outputs the water in one area, so there may be some dead spots in the fish tank. However, HOB filters do cascade the water back into the tank creating sufficient surface agitation.

A canister filter or sump will do a much better job of circulating the water in your tank, simply because of the increased power and the fact that you position the intake and output tubes on opposite ends of the tank. The same effect can be achieved by placing two HOB power filters on your fish tank. One on each side.

If you’re wanting to save money, then you would probably use a type of filter that works with an air pump, such as a sponge filter. These types are pretty inexpensive and cheap to run. Sponge filters work just fine in most cases, but take up a lot of room in your aquarium.

How long should you run the air pump?
It depends. Some people will run them 24/7 and others will turn it off at night. If you have sufficient filtration, it’s not really necessary to keep them on all the time. Most air pumps get kind of noisy with a distinct humming sound, so if it’s in your bedroom it could get somewhat annoying. Unless the sound relaxes you. They don’t use much electricity, so cost shouldn’t be much of a factor.

So, I would say leave it on 24/7 unless the noise is getting to you.

Final Words

An air pump is a good addition to your fish tank, but not totally necessary if you have decent filtration. Air pumps keep the water oxygenated and help circulate dead spots.

Most air pumps have a humming sound. The higher they are turned up, the louder they get. There are some more expensive models that are pretty quiet, so if you want to make the investment, look at the Eheim 400.

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