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. This simple foam cylinder has a hole in the middle that allows you to slip it onto the intake tube of your filter, much like a sock. Why would we need a prefilter sponge if we already have an aquarium filter. There are many benefits to intake sponges, including:

– 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 provides more mechanical filtration and prevents your filter media from becoming dirty as quickly. 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?

Our sponges come in three sizes – mini, medium, and large – and we purposely designed them with coarse foam that has larger 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 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




Zip tie it to keep it in place









Slim S10

Slim S15


Slim S20


Emperor 400

Penguin 75

Mini 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 EX20

Whisper EX 30

Whisper EX 45



Whisper EX 70



Use a thick O-ring or zip tie to make it stay

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 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. 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.

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:

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. Slide the pre-filter sponge over the O-ring on the tube, and the sponge should stay put. – 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. The buckle should still be attached to the tail. Slide the sponge onto zip tie on the intake tube for a very firm fit. – Cut off a small rectangle of coarse sponge pad and slip it inside the intake sponge. Make sure the intake sponge is properly positioned on the tube.

Zip Tie Attached to the End of an Intake Tube to Keep the Intake Sponge from Slipping

You can make your own prefilter sponge if the tube is unusual. 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.

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. If the water output of your filter is decreasing, or once a month, you should “empty the trash” to clean your prefilter 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 pre-filter sponge back onto the intake tube. 6. You can wait for the filter to remove any particles that are still in the water.

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.