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  • Molly Weinfurter

Pros and Cons of an Aquarium Sponge Filter

Updated: Jun 12

An aquarium sponge filter is one of the most common filter types for a fish tank. However, when you’re setting up your tank, how do you choose what kind of filter to use? Let’s look at the basics of sponge filters and determine the pros and cons of an aquarium bio filter sponge.

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How Does a Sponge Filter Work?

A sponge filter consists of a piece of sponge that sits in your aquarium and an air pump that sits outside the aquarium. Then, the two are connected using tubing. The air pump pushes air through the tube and into the sponge filter to create bubbles inside the aquarium. An air stone can be added to the sponge filter to increase the bubble production.

When the bubbles rise from the sponge filter, the water flows through the sponge. Then, the sponge collects debris from the water in the process, helping to clean the tank water. The sponge also acts as a place for beneficial bacteria to grow. As long as the sponge filter is cleaned regularly, it continuously keeps the tank clean.

When Should You Use an Aquarium Sponge Filter?

Sponge filters are great for most tanks, especially if you’re looking for gentle filtration and an easy-to-clean product. They’re ideal for small tanks with small fish that would easily get sucked up in other types of filters. They can be used for larger tanks, but you’ll likely need more than one sponge filter to keep all areas of the tank clean.

Yet, if your aquarium gets dirty quickly, a sponge filter might not be right for you. Other types of filters have several layers of filtration to more effectively clean the tank, which may be better for messy pets. Sponge filters also produce a lot of bubbles, so it may not be ideal for pets that get scared of movement in the tank.

How to Set up a Sponge Filter

To set up a sponge filter, follow these steps:

  1. Gather all the necessary supplies: sponge filter, air tubing, air pump, check valve, and airstone.

  2. Take apart your sponge filter and add an airstone inside (not required, but recommended).

  3. Reassemble the sponge filter.

  4. Attach tubing to the top of your sponge filter.

  5. Put the sponge filter in the aquarium. If it doesn’t sink to the bottom, squeeze it several times to get the air out.

  6. Cut the tubing long enough so the other end can connect to the air pump. 

  7. If the air pump is below the sponge filter, add a check valve. Cut the tubing a few inches from the outside of the aquarium and then put the check valve in between the two tube pieces. The banded side of the check valve should face the air pump.

  8. Plug in the air pump. Make sure the cable dips down lower than the plug so water cannot reach the outlet.

Learning to set up any type of aquarium filter is typically easier with a visual example. This is a great video for showing how to set up a sponge filter.

Remember that not every filter is the same. The sponge filter you purchase may be slightly different than the ones you see in videos. Look at your sponge filter instructions for tips on how to set it up.

How to Clean a Sponge Filter

Once your sponge filter is set up, it’s easy to maintain it. It should be cleaned about once a month, but you may need to clean it more often if you notice a drastic decrease in bubbles coming out of the filter.

Here are some steps for how to clean your sponge filter:

  1. Take the sponge filter out of the aquarium and remove the top part.

  2. Remove the sponge part from the rest of the filter.

  3. Using some old tank water, dip the sponge part into the water and squeeze it. Keep squeezing it until you get all the dirty water off the sponge. It’s not recommended to clean it with tap water because it could harm the beneficial bacteria in the sponge.

  4. Reassemble the sponge filter and place it back in the aquarium.

Again, this process could vary slightly depending on the exact sponge filter you buy, but for the most part, cleaning a sponge filter is pretty straightforward.

goldfish in aquarium

Pros of an Aquarium Sponge Filter

Below are some of the many reasons people choose sponge filters over other filter types.

It’s Cost Effective

Sponge filters are the most affordable filter type. Not only are they affordable to begin with, but they require little maintenance and power usage. While hanging filters and canister filters require you to change some of the media every month, the sponges on sponge filters only need to be replaced every four to six months. So, sponge filters are cheaper than other filters in the long run.

It’s Easy to Clean

When it’s time to clean a sponge filter, all you have to do is pull it out of the tank and squeeze the dirty water out of the sponge. This needs to happen about once a month or whenever you notice a decrease in bubbles coming from the filter. When it’s time to replace the sponge, you’ll simply switch it out for a new one instead of wringing out the old one.

You Can Run Several Sponge Filters at Once

One air pump can run several sponge filters at once. Having multiple sponge filters is often more effective than one large sponge filter because you can place them in several areas of the tank. Using only one air pump is beneficial because even though you have more than one filter, there’s only one plug in your wall.

It’s Great for Young Fish

If you have a bunch of fry (recently hatched fish), in your aquarium, a sponge filter is the way to go. Other filters might accidentally suck up the tiny fish, but a sponge filter can’t do that. If you use a hanging filter for a fry fish tank, you’ll need to cover the end in a layer of sponge anyway, so you might as well just use a sponge filter.

Helps Cycle New Tanks Faster

Sponge filters are great at holding beneficial bacteria. Once a tank is cycled with the sponge filter inside, you can move that sponge filter to a new aquarium to add beneficial bacteria into the aquarium, allowing it to cycle faster. However, even if you do that, you should still make sure all the water parameters are safe before adding animals into the tank.

It Provides Oxygen

Bubbles will continuously rise from the filter because of the air pump and air stone. Those bubbles are a great source of oxygen in your tank. Having a well-oxygenated tank is beneficial for the health of the animals. Without enough oxygen underwater, your pets may keep rushing to the surface to get some.

It Comes in Different Sizes

Sponge filters come in a wide range of shapes and sizes. Thus, you can choose one that’s ideal for your tank’s setup. As mentioned earlier, you can also use several smaller filters spread out in the tank rather than one large filter.

baby fish with sponge filter

Cons of an Aquarium Sponge Filter

There are lots of benefits to an aquarium sponge filter, making it a popular choice for most aquatic pet owners. However, like with any product, there are some potential downsides.

It’s Bulky

The biggest downside with sponge filters is that they take up space inside your aquarium. Hanging filters and canister filters are mostly outside of the tank, but sponge filters need to be submerged in the water. So, they can take up space that you would otherwise use for plants, hides, and other decorations. They can also be a bit unsightly.

It Doesn’t Provide Chemical Filtration

Other types of filters provide several layers of filtration: chemical, mechanical, and biological. However, sponge filters don’t have any form of chemical filtration. While chemical filtration isn’t necessary for every aquarium, it can more effectively clean the water. It’s up to the pet owner if they want all types of filtration in their aquarium or not.

It Can Be Loud

Sponge filters can be loud because of the air pump motor and the constant stream of bubbles. Yet, all filters will cause some noise, so it’s up to you to decide if a little extra noise is worth it. Placing a soft material, such as a towel or piece of foam, under the air pump motor can reduce the noise it makes from vibrations.

The Bubbles Could Stress Fish Out

Some animals, such as axolotls, could get easily stressed out by water movement. So, the stream of bubbles coming from the sponge filter could be too much for them. If you have a pet that’s sensitive to the water moving, you may want to consider a different filter type.

Gunk From the Filter Could Get Into the Water

Gunk and debris can build up in the sponge filter over time, which is why you should remove the sponge and wring it out monthly. If you don’t clean the filter enough, those gross particles could end up floating in the water instead of staying in the sponge. That gunk is an eyesore while also being unhealthy for your pets. So, make sure you clean the filter regularly to prevent that.

Where to Buy an Aquarium Sponge Filter

Even though I don't use a sponge filter, I've seen plenty of them for sale. You can buy them from pet supply stores or online retailers. Here are a few popular sponge filters on Amazon:

Frequently Asked Questions

Where Should I Place a Sponge Filter in the Tank?

If possible, place the filter toward the middle of the aquarium so it can effectively clean all areas of the tank. If you put it off to the side in a large aquarium, consider adding a second sponge filter for maximum filtration.

Where Can I Buy an Aquarium Sponge Filter?

Most pet supply stores that have aquarium supplies will sell sponge filters. You can also order them from many online retailers if you can’t find what you’re looking for in-store.

Why is My Sponge Filter Not Working?

If your sponge filter isn’t working, first make sure you’re cleaning and replacing the sponge frequently enough. Then, check to make sure all the tubing is connected properly and not clogged. Also, ensure the air pump is functioning.

Are Sponge Filters Better Than Hanging Filters?

It depends. Some people prefer sponge filters because they’re easy to maintain and cost effective. However, others prefer hanging filters because they typically clean the tank more effectively.

How Often Do Sponge Filters Need to Be Replaced?

You likely only need to change the sponge on your sponge filter every few months. However, if it’s getting worn down, you can replace it sooner if needed. There are plenty of replacement sponges online and at pet supply stores.

Small beta fish in aquarium

Consider an Aquarium Sponge Filter

An aquarium sponge filter can be a great filter for a variety of fish tanks. Overall, it’s cost effective, easy to maintain, and beneficial for small fish. However, it takes up space in the aquarium and can be loud.

It’s up to you to consider the pros and cons to decide if a sponge filter for a fish tank is right for you. It all comes down to preferences, the aquarium size, and the animals inside the aquarium.

I have an axolotl, and when I adopted him, I didn't know about sponge filters. I got a hanging filter for his tank (this one), and it works great. I like that it doesn't take up space in his tank and I would likely get the same type of filter if I got a second aquarium. Yet, sponge filters seem like great choices too, so consider the pros and cons of each filter type to decide which one you should get.


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