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How Do Sponge Filter Work – Set Up Guide

One of the most important aspects to keeping your fish happy and healthy is providing them with a clean and healthy environment. Of course, this encompasses a lot of different aspects such as the right level of lighting, the water pH and hardness, and of the course the general cleanliness.

As a result, most tanks will require some kind of filtration system.

While many of these systems are complex, over engineered beasts, one of the most popular types is the simple yet versatile sponge filter.

Filtration is a requirement for most healthy fish tanks, because it allows you to continuously recycle the water, clearing debris in the process, and promoting the growth of healthy bacteria which have a positive symbiotic relationship with your fish tank.

Sponge filters are just one example of a filtration system, but it is attractive for its simplicity and efficiency. Sponge filters are not like traditional, heavy duty filters.

And in this article, we will explore the differences between the two, highlighting the advantages and disadvantages of sponge filters and showing you how to install, use and clean these incredibly useful pieces of kit.

So, if you’re looking to providing your beloved fish with the cleanest, clearest water possible, with minimum fuss or hassle, then stick around as we answer, how do sponge filter work?

What are Sponge Filter?

You might wonder, just what are sponge filters for, and what purpose do they serve to the modern tank owner. Well, the answer is really threefold. Sponge filters are brilliant because they provide biological filtration, mechanical filtration and a certain degree of aeration. We’ll deal with each of these in turn.

Biological Filtration

Biological filtration refers to the work down by the tiny colonies of bacteria that like to make their home in the crooks and crevices of the sponge filters. In fact, bacteria will love to sprout up on most surfaces, and so the high surface are per unit volume of the wire mesh sponges create the perfect environment for these bacteria.

Unfortunately, some of us have a bad idea of what bacteria do, and may rush to the judgement that all bacteria are bad.

In actual fact, the bacteria in sponge filters do a very important job!

Because they convert a lot of the harmful waste by products that fish produce, such as ammonia, and reduce them into harmless substances.

This is extremely important for the overall health and sustainability of your tank, and without these bacteria, your fish could not thrive or even survive! Biological filtration is an absolute must have for tanks.

Mechanical Filtration

Sponge filters also work to mechanically filter the water. Unfortunately, it’s not just ammonia and phosphorous compounds that are found in your tank water. There are also solid particles of dirt and debris, which can reduce the clarity of your water.

Obviously, this is bad for you as an observer, but it also has a negative impact on your fish’s health. Luckily, sponge filters can trap and condense all this solid waste, allowing you to easily remove it when you do your regular cleaning.


Finally, the importance of aeration in your water cannot be overstated. Usually, sponge filters are air driven, and they act as a source of oxygen in your fish tank.

This is important because fish require a certain amount of dissolved oxygen to stay alive, and if algae bloom threatens to take over your tank, this extra supply of oxygen might just help your fish stay alive.

In addition, the beneficial bacteria that labor in your sponge filter are aerobic, which means they require a steady supply of oxygen to do their job. This is provided by the air pump connected to the sponge filter, allowing you to keep your tank clean and clear.

How do Sponge Filter Work?

Video: “How Do Sponge Filters Work?”

The operation of these ingenious mechanical devices is actually very simple. The most basic sponge filters consist of two parts, a sponge and an air pump.

The sponge (often of a wire mesh construction) sits inside the tank. It is usually weighted so it does not float and instead sits on the bottom of the tank.

The air pump sits outside the tank, and supplies the air that the sponge needs to do its vital work.

The two components are connected by means of a simple tube. The air pumps are often low powered machines and may be relatively quire. Often they are even driven by the power from USB.

The air that is drawn in at the air pump is then forced through the plastic tubing to the sponge filter. This produces a stream of bubbles in the sponge, passing out and into the tank water. In turn this causes the water in the tank to circulate through the sponge, and this brings any dirt/debris or harmful ammonia into contact with the sponge walls, hence trapping all the unwanted nasty particles.

This is a relatively easy solution to providing biological and mechanical filtration, especially when compared with some of the complex back of the tank systems you see. It also helps to minimize the disruption to your fish, as the currents created are very small. This means that these types of sponge filters are suitable for even the smallest of fish.

This shows how do sponge filter work, and how the simplicity of their design is their real strength.

What are the Advantages of Sponge Filters?

There are numerous advantages to these little bad boys. For one, their simplicity is key. They are generally small and unobtrusive, meaning they can be installed in any tank or set up with minimum hassle or installation time.

This is very different to traditional filtration systems, which are usually specific to a certain type of tank and contain multiple stages and sub systems.

In fact, sponge filters are so versatile that they can even be installed where other filtration systems are already acting, either to enhance the filtration process or as a backup in case of failure of the main system.

Also, because of their relative simplicity, these systems are generally much more affordable compared to their larger competitors. They are very widespread and it is easy to pick up a very decent set up for less than $10. This is unimaginable with other types of filters.

There are many other perks besides this. For example, as mentioned above, sponge filters provide both mechanical and biological filtration in one handy package.

With many filtration systems, these two functions are very separate, and require at least two different purchases, but with sponge filters, it is all inclusive. This means that you can rest assured that your fish are not getting choked up on ammonia and other waste products, while at the same time getting cleaner and clearer waters due to the mechanical retention of solid wastes.

Safe for Shrimp and Small Fry

One of the other big draws of these simple sponge filter systems is that they are not only safe for shrimp and small fry, but they are actually beneficial! Many larger filtration systems threaten the safety and well-being of any shrimp or fry in your tanks, as they can easily get sucked into the filter or caught in its strong circulation currents.

Not so with sponge filters. There is really nothing for them to be sucked into, and the currents generated are not nearly strong enough.

In fact, the small enclosed spaces and surface area of the sponge filter is a natural resting and feeding place for shrimp and fry. So, many of them congregating around it, and eating any algae or food off its surface. This is yet another example of how do sponge filter work.

How to Set up Sponge Filters

Video: “How to Install a Sponge Filter + 3 Bonus Tips”

You may be wondering not only how do sponge filter work, but also how do you actually set one up. Well the process is actually very simple, and can easily be accomplished by even an inexperienced fish tank owner.

Firstly, you must make sure to properly set up the air pump outside the tank, make sure it has a suitable power supply, and connect the air tube at one end.

Next you should get to work on installing the sponge filter. You will have to connect the strainer to the base, and then connect this in turn to the air tube.

Then it is time to place the sponge filter around the strainer. This should easily slide onto the plastic body, and should make a tight fit.

Once you’ve done this, you should just be able to place the sponge filter in a suitable location in your tank, turn on the air pump, and let the device work its magic.

This is such a simple process, which is of course one of the main attractions of sponge filters.

How to Clean Sponge Filters

As was mentioned earlier, sponge filters are not just the substrate for the natural filtration bacteria that all fish owners know and love, they also have an important role in collecting the insoluble residue, dirt and general debris that forms or falls into your tank.

As a result of this mechanical filtration action, your sponge filter may get clogged up over time, and will eventually need to be cleaned. Fortunately for tank owners, this is an extremely simple process.

Firstly, you should disconnect the top part of the sponge filter from the base (i.e. disconnect the strainer and foam filter).

The next step is crucial. To prevent the detritus that is contained in the sponge filter from spreading back into the tank water, it must be handled very careful. As a result, you should envelop it in a plastic bag and then withdraw that from the tank, along with a lot of water on the side.

Now, once you have the sponge filter out of the tank, you should carefully squeeze and wring out the foam to remove most of the clogged-up dirt. You can also immerse it in fresh water to help with the process.

Remember that the bacteria colonies contained in the filter are very precious, hence you should avoid using too much force and definitely steer clear of using any harmful chemicals to clean your filter. This will destroy the beneficial bacteria, which will have long term negative impacts on your tank.

Once you’re happy with the cleanliness of your sponge filter, you can simply place it back in your tank, reconnect it to the base and top up your tank. By doing this you are making sure that your fish will have a clean environment for a long time to come.

How to Choose a Sponge Filter

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There are a lot of things to look for in a good sponge filter. For example, you should not overlook the quality of the build and the trustworthiness of the manufacturer, as this is a product that you will want to last for a long time in your tank.

However, this might be difficult to judge for a relative newcomer to this hobby. There are a lot of other parameters that you can be on the lookout for. For example, cost is obviously a factor, maybe the deciding factor.

You can invest in very good sponge filter set ups for a fraction of the cost of other filtration systems. You should also consider the surface area of the filter, the power of the pump and the size of the strainer.

One of the other things to consider is whether your sponge filter comes with an air stone.

An air stone is a small accessory to a sponge filter, which results in a fine, fast stream of very tiny bubbles, instead of intermittent larger bubbles. This results in much more efficient filtration and provides a source of constant aeration to your tank.


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This article has answered the pertinent question of how do sponge filter work? Whether you are looking at the filtration systems for your next fish tank, or considering an overhaul of your current set up, you should definitely consider using sponge filters.

They have a host of advantages including their lower costs, convenience of installation, smaller circulating currents and the incredible efficiency of their filtration.

As we have shown, this is in part due to the mechanical filtration, as well as the biological filtration and the helpful aeration.

All of these factors play a role in making sponge filters one of the most widespread and popular forms of fish tank filtration across the world. The process of both installing and cleaning sponge filters is very simple, as has been outlined in this text.

There are very few drawbacks to this method of filtration, so if it’s not already, it should definitely be on your wish list!

Aaron Boyd
Aaron Boyd

Hello, I’m Aaron Boyd, the proud owner and author behind Aqua Movement. I hope my article was able to answer your questions. If you want to learn more about me, click the home icon above.

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