How to Upgrade an Aquarium Filter (and Save Money!)

Have you ever bought a new hang-on-back filter from the pet store and noticed that the instructions say you have to change out the filter cartridge at least once a month? Most beginner fish keepers don’t realize that you can replace those disposable cartridges with reusable filter media that can last for the lifetime of the filter. In this article, we teach you how to optimize your aquarium filter in four simple steps, using only a pair of scissors.

Step 1: Get a Prefilter Sponge

Beneficial bacteria are a naturally occurring form of biological filtration that consume the toxic nitrogen compounds produced by your fish’s waste, thus making the water safer for the fish to live in. They tend to grow on any underwater surface, including the gravel and walls of your aquarium. Therefore, one of the easiest ways to encourage their growth is to increase the amount of surface area in your tank with a prefilter sponge. (If you aren’t familiar with the three types of filtration – mechanical, biological, and chemical – you can read our article called Fish Tank Filters: Which One Should You Get?)

A prefilter sponge is a foam cylinder that fits over the intake tube of your hang-on-back or canister filter, like a sock on a foot. Not only do prefilter sponges grow lots of beneficial bacteria, but they also help with mechanical filtration by preventing food, small fish, leaves, and other large debris from getting sucked into the filter’s motor compartment.

Pick an appropriately sized prefilter sponge for your filter, and you can easily double its filtration capacity.

Install the prefilter sponge so that it barely covers the slits on the bottom of the intake tube; that way the filter pulls water from the bottom of the prefilter sponge for maximum filtration. However, if you find your prefilter sponge is a little too loose, you can cut off a sliver of sponge and stuff it down the center hole to make a snugger fit. Also, if you notice that the water flow from your filter is decreasing, make sure to regularly clean the prefilter sponge about once a month by squeezing out the debris in a bucket of old aquarium water.

Step 2: Remove the Disposable Cartridge

At the beginning of the article, we mentioned that you should replace the default cartridge the filter comes with. But why is it so bad? The fact is that most cartridges are made out of fine filter padding for mechanical filtration (to remove debris from the water) with activated carbon inside for chemical filtration (to remove medications and other impurities from the water). Unfortunately, the fine filter padding and activated carbon quickly become saturated with waste and impurities, greatly lowering their effectiveness, and their dense materials are hard to clean and reuse.

Step 3: Install the Reusable Filter Media

Fill up the filter compartment (where the filter cartridge was supposed to go) with coarse foam sponge and bio rings. These filter media types are reusable, have much more surface area for biological filtration, and can increase the amount of capacity filtration by up to four times! As with the prefilter sponge, there is no need to constantly replace them and throw away all that beneficial bacteria; just rinse the filter media in old aquarium water once a month.

Coarse sponge pads remove debris from the water and can be reused by rinsing them on a monthly basis.

For mechanical filtration, we like to use coarse sponge pads that you can cut to fit any compartment in a hang-on-back or canister filter. We offer coarse sponges because they do not clog very easily, are fairly low cost, and can last 10 years or more. For biological filtration, you can use bags of bio rings that have lots of porous holes for beneficial bacteria to grow in. If the bag doesn’t fit perfectly into the filter, you can also buy a resealable filter media bag and pour the right amount of bio rings that will fit inside the filter compartment.

Bio rings help boost the growth of biological bacteria, which consume the toxic nitrogen compounds produced by fish waste.

In order to install the filter media, find out which direction the water flows through the filter. For example, in an AquaClear filter, the water travels upwards from the bottom of the filter compartment to the top and then falls back into the aquarium. Place the coarse sponge pad at the bottom of the compartment (so that the water hits it first), and then place the bio rings on top of the sponge. That way the coarse sponge removes most of the gunk from the water and the bio rings (which has smaller pores) won’t get dirty as quickly.

If you have a nano tank for your betta fish that comes with a built-in filter compartment, you may not be able to fit as many layers inside. Therefore, we recommend switching out the disposable cartridge with only coarse sponge, which provides both mechanical and beneficial filtration.

Step 4: Clean the Reusable Filter Media

Make sure to regularly maintenance your filter and rinse the filter media once a month. Mechanical filtration (such as prefilter sponges and sponge pads) acts like a garbage can that collects waste – which means you as the fish owner are still responsible for cleaning the filter media (in other words, “emptying” the trash can before it overflows and causes water to spill out of the aquarium).

How Do I Upgrade My Filter to Get Crystal Clear Water?

If you want to really polish the water, simply add a layer of fine poly pad that has very small pores and is capable of removing tiny particulate. Like the cartridges, these fine filter pads will eventually need to be thrown out and replaced once they become saturated with debris. However, the advantages are these pads are very cheap and can be cut to any size.

Poly pads are great at removing fine particles so that you get crystal-clear water and your fish look like they’re flying in midair.

Final Thoughts

Upgrading your filter with reusable filter media makes your aquarium system much more efficient and better at keeping the water quality high. The upfront cost may be a little more at first, but reusable filter media tends to last for the lifetime of the filter, saving you a lot of money in the long run.