Why you Need a Pre-Filter Sponge for Your Aquariums


Why You Need a Pre-Filter Sponge for Your Aquariums

You are looking for an easy way to optimize your hang on-back (HOB), or canister filter. Pre filter sponges (or intake sponges) are a simple way to optimize your hang-on-back (HOB) or canister filter. The simple foam cylinder comes with a hole in its middle. This allows you to slide it on the intake tube of your filter much like a sock. What good is a prefilter sponge? We already have an aquarium tank filter. Intake sponges offer surprising benefits such as:

– They provide more surface area to grow beneficial bacteria, which purify the waste chemicals in the water and make it safe for your fish to live in. Large openings in the filter intake tube can allow large objects to be sucked up and potentially damage the motor. The pre-filter sponge prevents things like baby fish, dwarf shrimp, little snails, plant leaves, and fish food from entering the filter. – An intake sponge adds more mechanical filtration, thus keeping your filter media from getting dirty as quickly. This is crucial because dirty filter medium can make it less efficient and we’d rather clean an easy to remove intake sponge than the filter material buried in a canister.

Prefilter sponge is installed at the tip of a filter intake tub

Which Pre Filter Sponge Should I Get?

We offer three sizes of sponges: small, medium, and large. Our sponges are made with coarse foam, which has a higher porosity. Pre-filter sponges won’t remove extremely fine particles, but will block most other particle sizes. They also won’t clog up as quickly. Our mini pre-filter sponge is best for smaller fish tanks and filters with slow flow, whereas the large pre-filter sponge is well-suited for bigger aquariums and filters with fast flow. To help you select the right size, see our chart that lists some of the most popular filters in the fishkeeping hobby:






Quietflow LED10

Quietflow LED 20

Quietflow LED 30

Quietflow LED 50


Quietflow 75 LED

Aquaclear 20

Aquaclear 30

Aquaclear 50

Aquaclear 70

Aquaclear 100

Use an O-ring, zip tie, or extra sponge to make it stay




To make it stick, use a zip tie









Slim S10

Slim S15


Slim S20


Emperor 400

Penguin 75

Miniature or medium

Penguin 100

Penguin 150

Penguin 200

Fit over the intake basket


Penguin 350

To make the basket stay put, remove it and attach an O-ring/zip tie.

Tidal 55

Tidal 75


Tidal 110


Whisper IQ 20 / 30 / 45

Whisper EX 20

Whisper EX 30

Whisper EX 45



Whisper EX70



Make sure it stays put with a thick O-ring and/or zip tie

A pre-filter sponge can also be used with our power head to transform it into a mini power filter. Just attach two zip ties to the powerhead’s intake basket, cut off the excess tails, and slide on a large prefilter sponge.

How to Install Pre-Filter Sponge

1. If the filter’s intake tube has a large basket that is much wider than the tube, then remove the basket. 2. The prefilter sponge should be positioned on the intake tube partially so that it only covers the tube’s tip. To ensure water flows more evenly throughout the sponge, the sponge should be placed at the end of the intake tube. This will prevent the foam from getting clogged as quickly.

O-ring attached on the end of an intake tube to keep the intake sponge from slipping

1. To make the sponge fit better, you can use the following methods:

You can get an O-ring set that includes many sizes. Find an O-ring that snugly fits on the intake tube, and position it about 1-2 inches (2.5-5 cm) from the end of the intake tube. The pre-filter sponge can be placed over the O rings on the tube. Attach a plastic zip tie around the intake tube’s end, approximately 1-2 inches (22.5-5cm) from the opening. Make sure the buckle is still attached by removing the tail. To ensure a tight fit, attach the sponge to the intake tube with a zip tie. – Take a small piece of coarse sponge and insert it into the intake sponge. Place the intake sponge on the tube and ensure it is securely in place.

Zip tie attached to the end of an intake tube. This will keep the intake sponge in place.

If the intake tube has an odd shape, you can still make your own DIY prefilter sponge. You can use a rough sponge pad to make a prefilter sponge.

To see a video demonstration of how to install and properly fit a prefilter sponge, watch our tutorial here.

How to clean a pre filter sponge

The intake sponge is essentially like a trash can that collects fish waste, old food, and other debris in the water. You should empty the trash can once a month. Also, clean the pre-filter sponge.

1. You can scoop the sponge out with a plastic bag. 2. Squeeze and wring out the sponge several times in old tank water inside the plastic bag. 3. The water that is dirty acts as mild fertilizer for plants. If you are able to, then pour the water onto the lawn or a houseplant. 4. Repeat Steps 2 and 3 multiple times until the water inside the bag is not very dirty. 5. Place the pre-filter sponge back onto the intake tube. 6. If there are lots of particles floating in the water, just wait an hour or so for the filter to clean it up again.

Adding an intake sponge to your filter is an easy way to upgrade your mechanical and biological filtration, while protecting your baby fish and invertebrates from getting sucked up. If you are not sure which aquarium filter to use, make sure to read our filtration guide for beginners.