Aquarium filters are essential to providing your fish with clean and healthy water. When it comes to choosing a filter for your aquarium, you have lots of options, and many fish owners can become overwhelmed. Regardless of the size of your tank, its inhabitants, and your personal preferences, we can guide you to the best options available. But no matter what type of filtration you select, remember that proper maintenance will keep it working long and hard.
Our best overall selection, the AquaClear Power Filter, comes in a wide range of sizes, contains filter media that is almost indestructible, and has been successfully cleaning the author’s tank for almost 10 years. When it comes to filters, you really can’t beat AquaClear overall.
The best choice for your aquarium filtration system is the AquaClear. This filter is a hang-on-the-back with a cleverly disguised foot brace to accommodate all sizes of aquariums. It has a basket that can contain any type of filter media you choose and comes preloaded with a durable sponge filter, a small bag of activated carbon, and zeolite media.
The sponge filter works well on its own, and we can attest that it can last up to 10 years. Remember: you NEVER want to replace your filter media!
The AquaClear comes in a wide variety of sizes at a reasonable price point and is relatively quiet. It’s also a great option if you have a saltwater fish tank. However, the flow may be too much for delicate finned fishes, such as bettas and fancy goldfish varieties in a small tank.
Sizes: 5-20 gallons, 10-30 gallons, 20-50 gallons, 40-70 gallons, 60-110 gallons | Output: 150 gph (maximum) | Filter Media: Sponge, carbon, zeolite
Expert Tip
“Filters are a vital component of any aquarium. Good fish health requires filters to be set up correctly and maintained regularly. All aquatic animals will require a filter of some kind,” Jessica Fox, DVM, a certified aquatic veterinarian at Marshall Animal Clinic in Minnesota, told The Spruce Pets.
When we tested internal filters, we found the Fluval U2 Underwater filter to be the best compact option for small aquariums. This type of filter rests within the actual aquarium so that it will take up a bit of space, but it can be customized, and it has a large filtering capacity.
Keep in mind that this filter may be mighty, but it’s still only suitable for small aquariums. It can be a little tricky to set at the right height and ensure the suction cups are solidly in place, but it’s a great filter for small spaces.
Sizes: 15 gallons, 12-30 gallons, 24-40 gallons, 34-65 gallons | Output: Not listed | Filter Media: Sponge
Need a quality filter with a low price tag? Then the Marineland Penguin Bio-Wheel is the best choice for your aquarium. Most models run under $30 and can suit many mid-size aquariums.
These filters feature a rotating paper filter, which is a pain to keep clean, so clogs are common. They also contain a mesh filter media packet, which should be replaced with a more solid sponge for better performance. Overall, this filter will provide your fish with adequate filtration for a low price.
Sizes: 10 gallons, 10-20 gallons, 20-30 gallons, 30-50 gallons, 50-75 gallons | Output: 75 gph, 100 gph, 150 gph, 200 gph, 350 gph | Filter Media: Paper, mesh, sponge
When it comes to providing filtration for a large system, you may want to consider using multiple filtration options in combination. However, if you are limited in power supply and space, you should check out the Fluval High Performance Aquarium Canister Filter, which can handle up to 250 gallons (FX4) or 400 gallons (FX6). Like its smaller counterpart also listed, this canister filter was smartly designed and comes with twin output nozzles for multi-directional flow return.
For ideal water flow, try to set up the intake and return as far away from each other as possible to move water throughout the tank. The Fluval Canister is also a great choice for larger saltwater tanks.
Sizes: 250 gallons, 400 gallons | Output: 700 gph (FX4), 925 gph (FX6) | Filter Media: Carbon, zeolite, biofoam, quick-clear, sponges
What We Like
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Includes programmable LED lighting
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High-quality filter media
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Available in multiple sizes
The Fluval Flex Aquarium Kit provides a tank equipped with a three-stage filtration system to maintain good water quality. There are three tank sizes to choose from, 9, 15, or 32.5 gallons, and the nine-gallon Fluval Flex Aquarium Kit is our top pick overall among small fish tanks. All three tank sizes make use of multi-directional dual outputs to filter through a minimum of 61 gallons per hour—plus, this feature allows you to change the water flow.
The filtration compartment is located in the rear, and you may find it hard to access for cleaning. On the back of the tank, there are pockets for both zeolite and carbon, which you can use or remove as needed for your aquatic life. The Fluval Flex even has space for a heater in the back filter area.
The tank itself is well-designed, with a curved front for a modern look, and is available with a black or white frame. The kit also includes a programmable LED lamp that encourages natural plant growth while enhancing the coloring of your aquarium and the species inside.
Sizes: 9 gallons, 15 gallons, 32.5 gallons | Output: 61 gph | Filter Media: Sponge, carbon, zeolite
What We Like
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Quiet filter
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Low outflow
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Can adjust flow
Tetra Whisper IQ is an upgrade from our previous selection of betta filters and is a great selection for fish with delicate fins and low-flow needs. In addition to taking up minimal space and having very quiet functionality, this filter also has adjustable flow. This makes it ideal for bettas in 5 to 10-gallon tanks. The included filter media is less than ideal, but just simply swap it out for our sponge recommendation below!
Note that this is not a great filter for all small tanks. Heavier fish loads will require a more robust filter. Since bettas are typically kept on their own, their waste and filtration needs will be minimal, making the Tetra Whisper IQ the ideal filter for bettas.
Sizes: 10 gallons, 20 gallons, 30 gallons, 45 gallons, 60 gallons | Output: 105 gph, 130 gph, 175 gph, 215 gph, 300 gph | Filter Media: Floss with carbon pellets
Sure, under-gravel filters may sound like a good idea, but unless you stay on top of your maintenance and have a low bioload in your tank, they do tend to clog. Once you have installed them, you are never going to get them clean again because cleaning requires complete disassembly of your aquarium, including removal of the substrate on top of your filter.
It is critical for you to carefully read the setup instructions and keep up with your maintenance. The Penn-Plax Undergravel filter contains plates, adjustable lift tubes, airline tubes, and activated carbon filters. This product works by an airlift system, and there is no air pump included, which will be required for this product to work correctly.
Sizes: 10 gallons, 20 gallons, 29 gallons, 55 gallons | Output: N/A | Filter Media: Carbon
What We Like
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Cut to fit any filter
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Durable dense foam
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Long-lasting
Not all filters come with the best filter media, so thankfully, you can swap it out for a Hipanda dense filter foam sponge. This filter media will last for years and not fall apart like many mesh or floss pads. This foam sponge can be cut to the exact shape of your filter, no matter which one you decide on.
To keep your nitrogen cycle running happily, never replace your filter media unless it is about to fall apart! To clean it, simply squeeze it out in some waste tank water and place it back in the filter casing. You’ll never need to buy filter media again. Use your savings to buy your fish some new decorations or some tasty treats.
Sizes: 7.5 x 4.7 x 2.75 inches, 9 x 9 x 1 inches, 10 x 4.7 x 2.75 inches | Output: N/A | Filter Media: Sponge
For hefty waste loads with fish that can stand up to a heavier water flow, you should consider a canister filter. The Fluval Performance Canister filter has been well thought out, has many handy features, and can contain a variety of filter media to suit your needs—though read the instructions carefully. When it comes to canister filters, cleaning and disassembly can be a bit of a pain, but the quick-release hoses and filter components with easy access handles make this filter less cumbersome.
While canister filters are rumored to be “superior” to standard hang-on-the-back filters, this is not true. Whatever filter system fits your fish, setup, and life cycle is just fine. They all get the job done of keeping your fish happy and healthy.
Sizes: Up to 30 gallons, 45 gallons, 70 gallons, 100 gallons | Output: 206 gph and up | Filter Media: Carbon, zeolite, biofoam, quick-clear, sponges
Fluidized bed filters can contain either sand or plastic bio media that is kept constantly churning by water flow, hence the term “moving bed.” These types of filters are typically not kept in systems on their own but as an additional filtration unit.
The QANVEE Fluidized Moving Bed Filter comes with K1-similar media that runs off an air pump. This filter has no moving parts and will also provide aeration to your tank, but you have to supply the air pump. This type of filter can be used in conjunction with other types of filters or as the only filter in aquariums with a very small number of fish and/or invertebrates.
Sizes: 2.6 x 7.4 inches (LH300), 3 x 9 inches (LH600) | Output: N/A | Filter Media: Plastic
What We Like
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Low flow for delicate species
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Free of moving parts
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Ideal for breeding tanks, shrimp, and bettas
What We Don’t Like
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Minimal filtration
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Clogs easily
Sponge filters, such as the Aquapapa Bio Sponge filter, provide filtration via an air lift system, where the movement of air bubbles from an air pump drives the water movement through the sponge. They are very delicate filters and best suited for shrimp tanks, breeding tanks, and betta tanks. These filters do not provide a ton of water flow, so you need to use them only in very low-bioload tanks.
Given their low water flow, these sponges can get easily clogged, so be sure to rinse them routinely in waste tank water. You will also need to provide an air pump, which is not included with your filter.
Sizes: 4.5 x 8 inches | Output: N/A | Filter Media: Sponge
Final Verdict
The best filter choice for most tanks is the AquaClear Power Filter, which attaches easily to nearly any tank and can use a wide range of filter media. And be sure to check out our updated selection for betta tanks, the Tetra Whisper IQ Filter, with its quiet function and adjustable flow for happy bettas.
What to Consider When Shopping for Filtration Systems for Aquariums
Filter Media Type
There are many different types of filter media available for home aquariums. Here are some of the types you may encounter:
- Mesh: This type of filter is very flimsy and cheap. It may contain a few flecks of activated carbon, but it’s mostly designed to fail. We recommend swapping this out for a sturdy sponge and cutting it to size before you start running your filter.
- Activated carbon: You are not required to use carbon in your filter. Carbon can be used to remove various compounds from your water, but your water may already be healthy enough. Carbon will deactivate water-based medications and some other water treatments.
- Sponge: This type of filter media should last you for several years. To clean it, wring it out in a bucket of waste tank water, such as after siphoning. Never replace it, unless it is about to fall apart, or rinse it in chlorinated tap water or heated water.
- Zeolite: These small ceramic rocks are designed to provide housing for good bacteria and bind with some nitrogen compounds. It will lose its absorptive powers over time but can be recharged in a saltwater solution.
- Plastic: These small beads are strategically designed with a high surface area for growing good bacteria with optimal water flow. These should be allowed to move around freely for best use.
Gallon Capacity
The bigger your aquarium, the more water you will need to filter. Most filters are designed to turn over the entire volume of the tank within 30-60 minutes. Any longer than that could have serious consequences for your fish and invertebrates.
Depending on your species and setup, you may need to go a little lower- or higher-powered filtration to provide the ideal environment. Bettas, for example, will require a lower flow, whereas some corals will require a higher flow due to their placement and anatomy.
Noise
Your filter should not be overtly noisy. However, the larger your filter, the more powerful the motor needs to be, so you may notice some noise. Never attempt to muffle the noise by covering or insulating your filter because this will cause it to overheat and malfunction. If you notice significant noise or increased noise from your filter, contact the manufacturer for troubleshooting.
Installation
There is no one perfect way to install a filter. Ideally, you should set up your filter to circulate all of the water within your aquarium. For hang-on models, you should ideally set up the intake towards the middle of your tank or opposite from a powerhead or aerator. This will create a current in your tank to ensure all of your water is filtered.
Canister filters require a bit more work to install. Usually, these are higher-power pumps that can create high currents in your tank. Try to baffle the outflow or direct it along the longest axis of your tank to prevent your fish from having to swim too much and wearing themselves out. With whatever filter you use, read the installation instructions carefully, and if you are unsure of anything, contact the manufacturer or visit their website.
Species Considerations
When choosing a filter, keep in mind certain species requirements. Goldfish, for example, produce considerable waste and can keep up with a stronger flow, so a more powerful filter is a good choice. However, fancy goldfish varieties, such as ranchus, orandas, or moors, with their physical modifications, will have more difficulty swimming in fast currents, so a different filter should be considered.
In faster-moving water, fish with swimming limitations can burn considerably more calories and get sick faster from starvation. Bettas are another species that will need a low-flow filter due to their ornate fins. You try swimming in a ballgown in fast currents, and you’ll understand!
FAQ
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How do aquarium filtration systems work?
Aquarium filters work by providing mechanical, biological and chemical filtration. Mechanical filtration removes particulates from your tank water produced by inhabitant waste. Biological filtration housing is provided in your filter media (types listed above). This allows beneficial bacteria to convert ammonia, the primary fish waste product, into nitrite and then nitrate, which is used by algae and plants as a good source and is not as toxic to fish.
Chemical filtration, such as that provided by activated carbon, changes the chemical composition of various compounds in your solution, such as chlorine and chloramines. As water passes through your filter, all of these filtration methods go to work on your fish’s environment, making it healthier for them.
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What are the types of aquarium filters?
There are many different types of aquarium filters.
- Hang-on filters: These filters hang on the side of your aquarium or tank
- Canister filters: These are external and self-contained and use hoses to run water back and forth from your aquarium
- Internal or box filters: These filters remain in the aquarium and must be fully or partially submerged.
- Under-gravel filters: These are plastic mats that reside under your substrate and capture debris. They need to be flushed regularly so the debris does not get trapped.
- Sponge filters: These are very simple filters that use an airlift from an air pump to circulate water slowly through a dense sponge.
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How do you clean an aquarium filter?
The best way to clean an aquarium filter may vary slightly depending on the type of filter you choose. It is recommended that you disassemble the various components per the manufacturer’s instructions. Rinse all of your filter media and components gently in a bucket of waste tank water, such as one collected from gravel siphoning.
Never rinse your media in chlorinated tap water or hot water. This will kill all of the beneficial bacteria you have worked so hard to cultivate! Before you plug your system back in, ensure that it is primed so the pump will work correctly and not get burned out.
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How often should I change my aquarium filter?
Never. You should never replace your aquarium filter unless it is broken or your filter media is literally falling apart. Just like in our cleaning recommendations, if you throw away your filter, you are essentially starting from scratch! Despite instructions to replace your filter every set number of months, please ignore them and use the money to buy your fish a new decoration or some fresh food.
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How do you determine which size filter is needed for an aquarium?
Most filters are listed by the total gallons of your system, which is a general sizing. If you have a lot of fish in your system, you may need a larger filter. If you have slow swimmers or fish with delicate fins (ex. bettas or fancy goldfish), you will likely need a lower flow, which may lead to issues with your filtration being insufficient if you have too much waste in your tank. Decreasing the total amount of fish in your tank will help decrease the load on your filter.
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What are early indicators that an aquarium filter is malfunctioning?
Signs of a malfunctioning filter will vary by the type. Sometimes, an insufficient or under-powered filter may not be apparent until weeks later when you test your water chemistry.
Air bubbles in your filter are a common issue and may result in low to no flow. If this occurs, read the instructions carefully on priming your filter for proper function. Loud noise from your filter is another common error.
Why Trust The Spruce Pets?
In her 10 years in private fish practice, Jessie Sanders, DVM, CertAqV, has seen thousands of home aquarium setups. Filtration and filters are discussed almost daily, and she has tried most of the models above for herself and her company. She’s even had the same AquaClear filter on her tank since 2014, with the same sponge!
She also consulted with Jessica Fox, DVM, a certified aquatic veterinarian with Marshall Animal Clinic in Marshall, Minnesota, for this story.
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