Why you Need a Pre-Filter Sponge for Your Aquariums

Why You Need a Pre-Filter Sponge for Your Aquariums

Looking for a very easy way to optimize your hang-on-back (HOB) or canister filter? Try a pre filter sponge (or intake sponge). 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. Why would we need a prefilter sponge if we already have an aquarium filter. Intake sponges have a surprising number of 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 on the filter intake tube allow for large objects to be absorbed by the filter. This could potentially cause motor damage. 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 increases mechanical filtration to keep your filter media clean. This is because dirty filter media can cause problems in the system. We would rather have an intake sponge that we can easily clean than filter media that has been buried inside a canister filter.

Prefilter sponge installed at the end of a filter intake tube

Which Pre Filter Sponge Do I Need?

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:




Pre-Filter size


Quietflow LED 10

Quietflow LED20

Quietflow LED 30

Quietflow 50 LED


Quietflow LED 75

Aquaclear 20

Aquaclear 30

Aquaclear 50

Aquaclear 70

Aquaclear 100

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




Use a zip tie to make it stay









Slim S10

Slim S15


Slim S20


Emperor 400

Penguin 75

Mini or Medium

Penguin 100

Penguin 150

Penguin 200

Place the intake basket over it


Penguin 350

Remove basket and use an O-ring or zip tie to make it stay

Tidal 55

Tidal 75


Tidal 110


WhisperIQ 20 / 30/ 45

Whisper EX 20

Whisper EX 30

Whisper EX 45



Whisper EX 70



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

To transform our powerhead into a mini-power filter, a prefilter sponge can be attached to it. 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 a Pre-Filter Sponge

1. Remove the basket if the filter’s intake tube contains a basket that is larger than the tube. 2. Slide the prefilter sponge partially onto the intake tube so that it is just covering the tip of the tube. Place the sponge at the very tip of the intake tube to ensure that water moves more evenly and foam doesn’t get clogged.

Oring to attach on the end an intake tube to prevent the intake sponge slipping

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

An O-ring kit with many sizes is available. Locate an O-ring which fits comfortably on the intake tubes and place it approximately 1-2 inches (22.5-5cm) from the tube’s ends. The pre-filter sponge can be placed over the O rings on the tube. – Get a plastic zip tie and tighten it around the end of the intake tube, about 1-2 inches (2.5-5 cm) 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. Slide the intake sponge onto the tube, and make sure it fits securely.

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. Use a sponge pad to cut a piece of sponge that you can either place inside your intake basket, or wrap it around the entire intake using zip ties.

You can watch our video tutorial to learn how to fit a prefilter sponge.

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. Once a month or whenever you see the water output of the filter has decreased, make sure to “empty the trash” and clean your pre-filter sponge.

1. To scoop out the sponge from the water, use a plastic bag. This will ensure that it doesn’t spread to the aquarium and cause a mess. 2. You can squeeze the sponge and then wring it out in the old tank water. 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. You can repeat Steps 2 and 3, until you are satisfied with the cleanliness of the bag. 5. Place the pre-filter sponge back onto the intake tube. 6. If you find a lot of particles in your water, wait for the filter’s to clean them up.

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. For beginners, our aquarium filter guide will help you choose the right filter for your tank.