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There are a million and one ways to hack the filtration in your fish tank to optimize its efficiency, save money and time, and more. Some of these methods are just gimmicks, while others are pure gold that experienced veterans in the fishkeeping hobby have discovered over time. After owning hundreds of aquarium filters in our fish store and personal fish rooms, we’ve narrowed down our top 5 simple tips and tricks for getting the best performance out of your filtration.

1. Switch to Reusable Filter Media

Have you ever gotten a hang-on-back (HOB) filter or an internal filter that was included as part of an aquarium kit and wondered how long the filter cartridge lasts? Unfortunately, many companies put disposable cartridges in their filters and recommend that you replace them every 1–3 months so that they can continually make more money. These disposable cartridges are usually made of a little bit of filter floss for mechanical filtration (to remove particles from the water) and activated carbon in the middle for chemical filtration (to remove medications and other impurities). The fine filter padding and activated carbon quickly become saturated with debris, which greatly lowers their effectiveness, and their dense materials are hard to clean and reuse.

Fortunately, you can replace the cartridges with reusable filter media like a coarse sponge pad and a bag of bio-rings. When the filter media becomes dirty, just wash them in a bucket of old tank water (without soap) and then put them back into the filter. Not only are you saving money, but you are also saving the beneficial bacteria living on the filter media, which serve as biological filtration to consume toxic organic waste and purify the water. These types of filter media often last for years and can be used to cycle new aquariums. There are even reusable forms of chemical filtration like Seachem Purigen. Unlike activated carbon, Purigen can be regenerated by soaking it in a solution of bleach and water, which “burns off” the absorbed toxins so it can be used again.

Replace the disposable cartridge with reusable filter media, like a coarse sponge pad cut down to the right size.

2. Don’t Forget the Pre-Filter Sponge

Using a intake pre-filter sponge is one of our best tips for a hang-on-back, canister, or other filter that has an intake tube. An intake sponge is simply a cylinder-shaped sponge with a hole in the middle that you pull over the intake tube like a sock. This simple accessory blocks fish food, dead leaves, substrate, baby fish, and invertebrates from getting sucked up and ruining the filter motor. As your first line of defense for mechanical filtration, the pre-filter sponge collects most of the gunk in the water before it reaches the filter media. By keeping the filter media clean, the filter runs more efficiently, and you can go for longer periods of time before having to clean your filter media again. Plus, the intake sponge provides extra surface area for growing beneficial bacteria and increasing biological filtration. We recommend using a coarse pre-filter sponge with larger porosity (even though they don’t catch as many particles) because fine sponges can become so clogged up that they put strain on and shorten the life span of your filter. For more info on which pre-filter sponge to get and how to make them fit perfectly, see our full article.

Cover all filter intakes with a pre-filter sponge for extra mechanical and biological filtration.

3. Hide an Air Stone in Your Filter

Normally, a sponge filter releases large, intermittent bubbles that start and stop like cars stuck in traffic during rush hour. By adding an air stone to the inside of the sponge filter, it breaks up those big bubbles into a steady stream of tiny bubbles. These little bubbles produce a constant flow of water through the sponge material, making the filter more efficient at trapping particles while lessening the bubbling noise. For details on how to install an air stone inside a sponge filter, read these instructions.

If you don’t prefer sponge filters, you can still place an air stone in your hang-on-back filter. Adding an air stone to the filter media compartment of the HOB filter helps to supercharge the growth of beneficial bacteria living there and infuses the water with greater amounts of oxygen so your fish and plants will thrive.

An air stone is a small, weighted accessory that diffuses the air from your air pump into smaller bubbles, helping to oxygenate the tank water.

4. It’s Possible to Add Carbon to a Sponge Filter

Many years ago, our founder Cory ran a tank maintenance business, and one of his customers was getting his wood floors stained. The whole house had to be vacated for several days because of the toxic fumes, and the customer was worried about the fish. As mentioned before, activated carbon can help absorb any tannins, medications, or other impurities from the water. Most people use it by pouring it into a filter media bag and placing it in the sump, hang-on-back, canister, or other filter that has a media compartment. But what if you need chemical filtration and only own sponge filters, which don’t have a filter media compartment?

Fortunately, you can get carbon-infused media pads. Normally, they are placed inside a filter’s media compartment, but you can also cut them down to size and wrap them around the sponge filter with a rubber band. As the bubbles travel up the lift tube of the sponge filter, they draw in water, which gets sucked through the carbon pad and the sponge filter walls. Over time, the toxins are removed as water continually filters through the carbon pad. This technique also works with other types of chemical filtration pads, such as ammonia filter pads and phosphate media pads.

Wrap the chemical filtration pad around a sponge filter and attach it with a rubber band.

5. More Filtration is Not Always Better

Many hobbyists, especially beginners, think that more filtration is better. They may cram multiple canister filters into a single aquarium or become fixated on reaching a high water turnover rate. In the past, Cory used to load up his big tanks with a sump, canister filters, and hang-on-back filter, but they took so much time to maintenance and were easy to forget about since he had so many filtration devices. Therefore, he slowly started removing one filter at a time and noticed that nothing changed, even when he was doing the same number of water changes as before. Eventually, he got to the point where each of his aquariums only had one filter and the water quality still stayed high.

Remember that each additional filter is another potential point of failure that may overflow, spring a leak, or have a cracked seal that causes flooding. Plus, owning lots of filters costs more money, uses more power, and takes more time to maintenance. When you only have one filter, veterans will tell you that you are more likely to pay attention to it in terms of cleaning the impeller and filter media, checking any weird sounds it makes, and having extra replacement parts. Focus on making your one filter as efficient as possible (with the hacks mentioned previously), clean it regularly, and do more with less. If you stay in tune with what you already have, it takes less effort to keep it running well.

Filters are not magical black holes that make waste disappear. Each filter you own is another device that must be regularly cleaned in order to run properly.

At the end of the day, everyone just wants the best for their fish so they live long and healthy lives. If you’re not sure which aquarium filter is right for you, check out our filter guide that explains 5 of the most popular options used in the hobby.