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). This foam cylinder is simple and has a hole at the center that allows you slip it onto your filter’s intake tube. It works much like a socks. 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. – The filter intake tube often has large openings that allow sizable objects to get sucked up by the filter, potentially ruining 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 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:






Quietflow LED 10

Quietflow LED20

Quietflow LED30

Quietflow LED 50


Quietflow LED 75

Aquaclear 20

Aquaclear 30

Aquaclear 50

Aquaclear 70

Aquaclear 100

You can make your sponge last longer by using an O-ring, zip tie or additional sponge




Zip tie it to keep it in place









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

Take out the basket and tie it with a zip or O-ring to keep it in place

Tidal 55

Tidal 75


Tidal 110


WhisperIQ 20 / 30/ 45

Whisper EX 20

Whisper EX 30

Whisper EX 45



Whisper EX70



To make it stick, use a thick zip tie or O-ring.

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

An O-ring kit with many sizes is available. 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. Slide the pre-filter sponge over the O-ring on the tube, and the sponge should stay put. 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. Slide the sponge onto zip tie on the intake tube for a very firm fit. Cut a small rectangle from the coarse sponge pad and place it inside your 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.

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