Why you Need a Pre-Filter Sponge for Your Aquariums

Photo of author


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? 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 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 important because dirty filter media does not function as efficiently, and we would much rather clean an easy-to-remove intake sponge than the filter media buried deep inside a canister filter.

Install a prefilter sponge at the end a filter intake tube

Which Pre Filter Sponge Should I Get?

There are three sizes to choose from: medium, large, and mini. We purposefully designed our sponges with coarse foam with a greater 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 LED 20

Quietflow LED 30

Quietflow 50 LED


Quietflow LED 75

Aquaclear 20

Aquaclear 30

Aquaclear 50

Aquaclear 70

Aquaclear 100

To make it stick, add an O-ring or zip tie to the sponge.




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 EX30

Whisper EX 45



Whisper EX70



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. Simply attach two zip ties on the powerhead’s intake tray, trim the tails, then slide on the large prefilter sponge.

How to Install a Pre Filter Sponge

1. You should remove any large baskets that are wider than the intake tube of the filter. 2. Place the prefilter sponge on the intake tube, making sure it covers the entire tube. The sponge should be positioned at the very end of the intake tube so that water travels more evenly through the entire sponge and the foam does not get clogged up as quickly.

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

1. You can make the sponge smaller by using one of these methods:

You can get an O-ring set that includes many sizes. 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 O-ring should be placed on the tube. Slide the prefilter sponge over it. Attach a plastic zip tie around the intake tube’s end, approximately 1-2 inches (22.5-5cm) from the opening. The buckle should still be attached to the tail. For a snug fit, slide the sponge onto the zip tie attached to the intake tube. – 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.

Even if your intake tube is not the most common shape, you can still make a DIY prefilter sponge. Buy a coarse sponge pad and cut off a section of sponge to a) stuff inside the intake basket or b) wrap around the entire intake and attach 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. You can scoop the sponge out with a plastic bag. 2. You can squeeze the sponge and then wring it out in the old tank water. 3. The dirt water acts as a mild fertilizer, so if you can, pour it onto your lawn or houseplant. 4. Repeat Steps 2 and 3 multiple times until the water inside the bag is not very dirty. 5. Place the prefilter sponge back on 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.