Sponge Filters: The Easiest Fish Tank Filter Ever

Sponge Filters: The Easiest Fish Tank Filter Ever

Sponge filters are one of the most popular filters used in fish stores, fish rooms, and breeding tanks because they’re so reliable and easy to use. However, beginners often have questions about how sponge filters work, how to set them up and how to maintain them. To help you get started with your sponge filter, follow our step-by-step directions.

Diagram for sponge filter setup

What is a Sponge Filter?

The most basic filter requires at least three components. A sponge filter, which sits inside the tank, an air pump (which is outside the tank), as well as airline tubing to link them. The air pump pushes air through the tubing into the hollow cavity inside the sponge filter. The sponge walls draw water through bubbles that rise from the sponge’s interior. This water suction process mechanically collects debris from the aquarium and gives beneficial bacteria place to grow.

Sponge filters are a long-time favorite of both beginner and veteran fish keepers since they’re cheap, easy to clean, and hard to break since they have very few mechanical parts. Because of the constant bubbling, it provides good water circulation and surface agitation, white being gentle enough to avoid sucking up fish fry, shrimp, and other slow-moving creatures. Plus, during power outages, the beneficial bacteria on the sponge stays in the oxygenated tank water (which gives it a longer chance of surviving), and you can even purchase a battery pack backup that works with our USB air pump in case of emergencies.

For more information on filtration options, read our article on fish tank filters and which one you should get.

Do I need an air stone for sponge filters?

An air stone is a small weighted accessory that diffuses the air from your air pump into smaller bubbles in the water. To reduce the noise from the sponge filter and increase efficiency, we recommend that you add an air stone inside. The airstone creates small bubbles that are steady and continuous, rather than intermittent large bubbles that move in a slow fashion. This gives the sponge filter constant lift.


How to set up a sponge filter

1. You can remove the sponge filter by removing the plastic strainer.

1. Take the bullseye off the strainer and place the airstone at the bottom. Connect the air stone to the nipple or center of the bullseye using a small length of airline tubing. The sponge filter can be connected directly to your bullseye, if necessary. 2. Snap the bullseye onto the top of the strainer, put the strainer back inside the foam, and then connect the strainer to the weighted base of the sponge filter. 3. The lift tube should be placed over the end of the roll of airline tubing. Connect the cable to the nipple at the top of your bullseye. Then snap the lift tube onto the bullseye. 4. Place the sponge filter into the aquarium and squeeze out any bubbles from the foam if it’s floating. 5. The air pump should be placed in the tank’s final position. Next, cut the airline tubing (attached with the sponge filter) to the right length. The sponge filter’s air tubing has been connected to the pump. 6. If the air pump is located below the top of the aquarium, you need to add a check valve to prevent water from flowing into the airline tubing whenever the air pump is turned off or the power is out. Cut the airline tubing (between the sponge filter and air pump) a few inches outside of the aquarium, and then attach the check valve in between so that the end of the check valve with the flapper (looks like a colored or horizontal bar usually) is facing the air pump. (If you install it backwards, no air will flow when you turn on the air pump, so just flip it around.)

1. To prevent moisture from getting into the plug, create a drip loop using the power cable. Then plug the pump in. After a few seconds you will see bubbles from the sponge filter.

Why Are Bubbles Coming out of the Side of the Sponge?

There could be many reasons this might happen. Check out the following:

– Did you shorten or remove the lift tube? A shorter lift tube does not have as much suction pulling bubbles up the center column, so some air may escape. – Is there a crooked air stone in the sponge filter? You may have to reduce the length of the tubing connecting the air stone to your bullseye to make it hang straighter. Is the pressure of the air pump too high? If a bunch of air is forced into the sponge filter, excess bubbles may leak out the sides.

Which Sponge Filter Do You Recommend?

Sponge filter are a very basic piece, so there isn’t much to choose from. After using hundreds of sponge filters for a decade, we decided to make our own. The base and lift tube were designed with a green color to blend with the planted tanks and hide green algae growth. The foam sponge is black to conceal any fish waste or other debris that might get sucked in.

The sponge is made of a coarse foam at 20 ppi with medium porosity. It can easily collect particulate and prevents it from clogging up. The surface area is ideal for shrimp and fish to graze on and clean. Plus, the coarse sponge doesn’t trap as much air, allowing it to get nice water flow and sink immediately. (Fine sponges often have problems with floating, which can cause lack of oxygen in your aquarium and potentially loss of life.)

The sponge filters that we sell are hollow in the middle and high enough to allow you to install an airstone inside. This will increase efficiency and create quieter bubbles. You can also connect another sponge filter to the top of the lift tube (without its base), to increase your filtration capability. You can customize these sponges in many configurations. All three sizes of sponges (except the nano sponge) are interchangeable. A stacking of sponges is more efficient than running them individually. They can all run on a single line of air pump. You can also remove one sponge from the stack to create a hospital tank. The sponges are already seeded and ready to go for quarantine.

How to Clean a Sponge filter

Yes, a sponge filter helps to clean your aquarium, but it’s essentially like a trash can that collects waste and needs to be emptied out every once in a while. Your sponge filter should be cleaned once a month. If bubbles are starting to fall, it is likely that the foam has become clogged with debris.

1. When taking the sponge filter apart, disconnect the bullseye from the strainer (i.e., take off the whole top part of the filter) so you can easily remove the foam part for cleaning. 2. Use a plastic bag to scoop the foam out of the water so that the detritus won’t spread and make a big mess in the aquarium. 3. Use old tank water to squeeze and wring foam out. 4. Now, assemble the sponge filter and place it back in your tank. 5. You can wait for the sponge filter to remove any large particles that are floating in the water.

Sponge filter are simple to use, cost-friendly, and more reliable than other types of filters. If you haven’t tried one yet, check out our line of sponge filters and let us know what you think!