Guide to Choosing the Best Aquarium Filters

Fish are fantastic pets, but they’re not the cleanest animals on the planet. Whenever fish do their business, everything is left floating around in the tank for all to see. To ensure a clean and healthy habitat for your fish, a filter is essential. The best aquarium filters maintain consistent water quality and provide crystal-clear tank water. This allows you to enjoy watching your fish thrive in a friendly and livable habitat.

The better the habitat you create in your aquarium, the better health your fish will have and the longer they’re likely to live. They’ll swim around more happily, shine with brighter colors, and keep you entertained. Even the smallest fish tanks need filters. Tiny tanks actually need them just as much as larger tanks, because the small space inside causes water quality to change more quickly because ammonia and other waste cannot dilute as much. There are filters built for every size, shape, and type of tank you could imagine. It’s up to you to choose the best aquarium filter to run in your home or commercial tank!

What to Look for in an Aquarium Filter

There are a few things that will be listed on product descriptions for filters. There’s no outright best fish tank filter for all tanks, so you need to understand a few things about what differentiates one filter from another to make an appropriate choice for your own tank. Here are the main things you need to know:

Product descriptions of aquarium filters provide essential information for making an appropriate decision. There is no outright best fish tank filter, so understanding the factors that differentiate one filter from another is crucial. Here are the key points you need to know:

Filter Capacity:

It’s worth emphasizing again that aquarium filters need to be matched to aquarium size. You can’t tell water quality by looking at the water itself, but it could be affecting the health of your fish, live plants, and other marine life. Filters should not be overworked.

Matching the size of the aquarium filter to the tank is crucial. Water quality cannot be determined by appearance alone; it directly impacts the health of your fish, plants, and marine life. Filters should not be overloaded.

For example, if your tank holds 55 gallons, the filter should handle at least that amount, if not more. It is better to choose a filter with a higher capacity. Your fish and plants rely on the filter to maintain a healthy environment. An undersized filter could result in the loss of aquarium life.

Fish and Plant Population:

In addition to tank size, the number of fish and plants in your aquarium affects filter selection.. A good fish tank filter should be able to keep up with your fish load without the water quality reducing too quickly. The more fish you have, the stronger your filter (or filters) needs to be to keep up with all of their waste.

A general rule of thumb is to allow 1 inch of fish for every gallon of water in the aquarium. For instance, a 30-gallon tank should accommodate no more than 15 two-inch fish or 10 three-inch fish, or a combination thereof. Consider this as an upper limit rather than a recommendation for fish stocking. Tanks with a higher fish load require a more powerful filter, often rated for a larger tank, to maintain optimal water quality.

Flow rate:

Filters are rated based on capacity and power (to determine how many gallons they can handle), but flow rate is another important consideration. Flow rate refers to the speed at which tank water passes through the filter.

Ideally, the filter should be capable of completely cycling the tank water within four hours. For example, a 30-gallon fish tank requires a filter with a minimum flow rate of 120 gallons per hour (GPH). Note that the listed flow rate represents the maximum GPH under ideal conditions. In reality, the actual flow rate may be lower, so keep that in mind during your filter selection process.

Aquarium Filter Brands:

As with any product, certain brands are known for producing reliable filters. Some well-known filter brands include Tetra, Fluval, Marineland, EHEIM, Penn Plax, and AquaClear.

While these brands are not the only reliable options, they have gained recognition for consistently delivering quality products. Choosing trusted brands doesn’t guarantee a superior filter, but it increases the likelihood of finding a product that performs as expected.

Top 10 List of the Best Aquarium Filters

1. AquaClear Power Filter

As a larger power filter, your tank will get mechanical, biological, and chemical filtration from this filter option. There is space inside for three cartridges, one for each type of filtration media. The space allocated to cartridges provides a large surface area for each, making for better biological filtration throughout.

Each cartridge can be individually replaced, so you can choose what to put in each slot and you can change them one at a time to avoid losing beneficial bacteria in the process of cleaning. When you purchase the filter, it comes with an AquaClear foam insert for mechanical filtration, and AquaClear activated carbon filter cartridge for chemical filtration and an AquaClear Biomix filter with ceramic rings for biological filtration.

Water is drawn into the filter from a long tube that sits inside the tank. At the bottom of the intake tube, there is a protective piece to block fish from being sucked inside. The intake brings water through the U-shaped tube and into the bottom of the filter, where the water then rises through the filter media and pours back into the tank.

It’s recommended to clean this filter every two weeks. Filter media does not need to be replaced every time the filter is cleaned, so you won’t have to do a lot of regular upkeep. You can adjust the flow speed to customize your filter’s performance and to help accommodate fish who may not like a higher flow rate.

2. Penn Plax 1500 Elite

No matter which size you get, this canister provides mechanical, biological, and chemical filtration. The elite versions also include an algae magnet to help keep the tank cleaner and free of unwanted algae. Each piece of filter media is stored inside its own separate tray, with each tray stacking on top of the other inside the pressurized cartridge. Each filter kit comes with bio-foam, bio floss, ceramic rings, and pro carb while the elite kit also includes the algae magnet.

Tubing and syphon suction heads help to create the pressurization for the filter. Tube heads can rotate 360 degrees, so you can place the filter anywhere around your tank without worrying about directional access to the water. Media trays are large enough to accommodate an effective amount of each type of media and do not need to be changed often. The canister itself has an air-tight seal, so it stays cleaner inside and keeps noise at a minimum.

3. Penn Plax Cascade HOB Filter

With plenty of space inside the filter area, you’ll get mechanical, biological, and chemical filtration through different cartridges. There’s a wide surface area for each filtration media, making it highly effective for the growth of beneficial bacteria.

It’s very easy to set up and clean out the filter whenever it needs maintenance. Cartridges don’t need to be changed every time cleaning is done and can be replaced incrementally to save the biological media. Bio floss and activated carbon cartridges are included so you can get started as soon as it arrives.

This is a hang-on filter that can be attached to any part of the back of the tank. It slips over the top of the glass to fit seamlessly in any aquarium. There’s a leveling device to help make sure the filter will operate properly even if it’s not exactly level and centered on the aquarium. A motor powers the filter and causes it to draw water from the tank through a long U-shaped tube. The water goes to the bottom of the filter and flows slowly up through the filtration media, pouring back down into the tank from a waterfall. The flow rate is adjustable to lower settings.

4. Fluval External Filter 406

All three types of filtration are provided within this canister filter. There are enough spaces for multiple types of cartridges, in case you want to focus on a certain type of filtration over the others. The square canister shape holds more water when in use than round canisters, giving greater surface area to filtration media and creating better water flow. All cartridges can be changed out individually and placed wherever you want them, giving you the freedom to customize the filter to suit the needs of your tank specifically.

Pressure is created through a closed intake system and air-tight canister. The intake hose has a clog-proof strainer to avoid sucking up small fish or larger pieces of debris from the tank. As a larger canister filter, it needs to sit outside of the tank on a stable surface and cannot be hung from the edges or the back.

5. EHEIM Classic External Filter

Inside the filter, you can put any type of filter media that you want. It does not use cartridges, so you’re not limited by specific size and shape. You can use loose-fitting filter media poured one on top of the other, filter sponges of the right size to fit into the canister well, or some combination of both together. The kits each come with some filter media from EHEIM that will provide mechanical and biological filtration. You can add your own activated carbon or other chemical filtration if you feel the need to.

The intake hose connects directly to the bottom of the filter rather than taking water through a U-valve to reach the bottom of the filter area. Water is then pushed up through the filter media and returned to the tank through the outlet hose on the top. All accessories for setting up the filter, including an optional spray bar, are included in the kit. Oxygen enrichment during the filtration process helps beneficial bacteria to thrive while also putting more breathable air into the tank water.

6. Fluval Fx6 Canister Filter

You will get mechanical, biological, and chemical filtration from this filter in any order that you choose. You can set up the filter media area to accommodate 3 different types of media in large quantities. There are 11.5 liters of area inside the canister, broken down into three even sections, to contain the filter media. When you seal the canister lid, you can lock it in place with multiple screw tabs to help avoid leaks.

All the parts necessary to use the filter are included with the kit. You’ll be the canister itself, all the hoses and tubes, as well as o-rings and seals and other auxiliary parts used for the setup. Nozzles that connect the intake and outlet hoses are multi-directional to give you more options when you’re installing the filter around the tank. It’s recommended that the filter be installed below the tank itself, not at the same level or above it, in order for the syphon suction to work at full capacity.

7. Marineland Penguin Power Filter

Your tank water will receive mechanical, biological, and chemical filtration. Each filter slot is fitted with a complete cartridge containing all three types of filtration media. Cartridges are compatible with either Rite-Size A, B, or C filter packets, depending on the filter model, so you can easily replace them with the cartridge of your choice. A patented Tetra BIO-wheel rests at the water outlet to get rid of ammonia and to act as a habitat for the beneficial bacteria your tank needs.

A little setup is needed for installation once you get the filter. All parts needed to begin using the filter are present in the set, including the filtration cartridge(s) and BIO-wheel(s). You can easily turn off and disassemble the filter to clean it as needed. Filter cartridges are recommended to be changed monthly, but the BIO wheel doesn’t need to be changed at the same time as the cartridges.

8. Tetra Whisper Power Filter

You get all three types of filtration from this filter. All of the filter inserts needed to do the initial setup are included with the kit. You can easily replace any of the filter media to make sure you’re getting the best out of your purchase. There are three separate slots for filter media on each side, which you can arrange as you please. The intake tube is in the middle and brings water down to the bottom of the cartridge area.

All assembly pieces are in the kit to get the filter working in your tank. The intake tube in particular comes in three different sections equaling to 16 inches in length, but it can be shortened by removing as many of the sections as necessary. Water is cascaded back into the tank from the top of the filter. You can easily adjust the flow rate by twisting a knob on top.

9. Fluval C Power Filter

These filters have five stages of filtration, separated into 5 different cartridge areas. Two stages are mechanical filtration, 1 is for chemical filtration, and the other 2 are for biological filtration. Foam pads, activated carbon, and biological filtrations media are all included with the filter to help you get it set up more quickly.

All water going through the filter is re-filtered multiple times to remove as many impurities as possible. Biological media included is a package of C-nodes, which can be replaced gradually in order to preserve beneficial bacteria growth.

The intake tube sticks straight down into the tank and can be extended with the proper tube attachment. You can adjust the flow easily by twisting a knob on top to either low, medium, or high. There are 15 total pieces that come with the kit (including filter media), with instructions to help you get it up and running right away. When cleaning is necessary, the filter has a built-in mechanism to alert you so you can always keep it in its best shape.

10. Hydor Professional Canister Filter

You’ll get all three types of filtration from this canister. Each filter media can be replaced separately and arranged to fit what you need most. You can choose to swap out any type of filtration for another type if you want to build up more filtration of a certain kind. All the media you need to get started is included with each filter kit, no matter which model you purchase.

Intake and outlet tubes create an air-tight syphon seal inside the filter system. The rectangular shape helps to provide a little more contact with the filter media inside without allowing water to slip unfiltered. An optional spray bar comes with this kit for the outlet bar, to let you adjust how water is returned to the tank to make it more suitable for different types of aquariums. The flow rate is adjustable as well, giving you a little freedom to make this filter work just how you want it to.

More Information on Aquarium Filters

Types of Aquarium Filtration

Before I say anything else, I must mention that there are three different types of filtration: mechanical, biological, and chemical.

Mechanical filtration removes particles from the water. This is what helps to keep your water clear and free of floating particles or debris. Mechanical aquarium filtration removes different-sized particles by running them through various types of media. Filter media is porous, with holes that are larger or smaller to remove particulates up to a certain size.

Biological filtration targets the micro-life inside your aquarium. Waste from fish and other life in the tank creates toxic byproducts in the tank water. In a wild body of water, natural inhabitants of the water break down waste, which you can simulate in your own aquarium.  By harboring beneficial water bacteria, biological filtration encourages the breaking down of ammonia into nitrates, which can then be utilized by plants or removed through regular cleaning and water changes.

Chemical filtration is not usually accomplished by an aquarium filter, but may sometimes be needed for your system. This type of filtration deals with harmful, toxic, or unwanted chemicals in your water that affects water quality. Picky fish may have specific water quality preferences that require you to do some sort of chemical modification or filtration. If your normal tap water has high levels of harmful chemicals (such as chlorine), chemical filtration may be necessary in your filter to maintain healthy water chemistry. Water treatment outside of filtration can replace chemical filtration.

Types of Aquarium Filters

There are many different styles of filters you can get for your aquarium. The best aquarium filters just have to fit your needs, no matter what style they are. However, different styles suit different types of tanks better than others. Choose the style that will work best with your aquarium.

Internal filters sit inside the aquarium, usually at the top of the tank. They can be mounted with suction cups, nestled on top of the substrate, attached to the corner of the tank, or fixed in another way. Many of these filters rely on air to push up from the bottom of the filter and move water through it. They often contain sponges and may contain activated carbon. These are often low-flow filters intended for smaller tanks and fish loads.

Under gravel filters rest underneath the gravel substrate in your tank and work by drawing water in through slots on the top. They use either an air tube or a low-flow suction tube to bring tank water and waste into the filter. Most under gravel filters focus on mechanical filtration rather than biological or chemical filtration. They only work for smaller tanks and will take more maintenance than other types of filters.

Hang on back filters, also called power filters, hang on the outside of the tank with a small tube that reaches inside to cycle water through. The large hanging part of the filter can be broken down into multiple cartridges containing media for mechanical, biological, and chemical filtration. External filters are easy to maintain and come in a wide range of sizes for different tanks. They are not ideal for aquarium life that can be easily disturbed by strong water flow.

Canister filters are installed outside the tank and form a pressurized flow of water. They draw water in with a syphon and run it through separate filtered sections that usually accomplish all three types of filtration. As a pressurized system that doesn’t require gravity or air to move water, mechanical and chemical filtration is excellent in these filters while biological filtration is limited. You can find canister filters sized for various tanks and fish loads.

Wet/dry filters have two parts. One part sits outside the tank while the other sits inside to collect water. Water is siphoned into the interior part and sent through a tube out into the external filter section. These filters don’t provide a high level of mechanical or chemical filtration, but their access to oxygen promotes biological filtration. While they don’t require much maintenance, they can be pricier than other types of filters. They’re one of the best filter styles for large fish loads, but not for heavily planted tanks.

Sump filters are receptacles that have all the necessary media for filtration, a heater, and a water pump. In the past, sumps were used only in saltwater tanks, but today they’re used in both saltwater and freshwater. They have a simple design and are very efficient, especially for larger tanks. It’s also worth mentioning that sumps or sump filters are great because they have the ability to store more media than your usual filter. With their help, aquarium owners can bring additional water volume to the system which is certainly beneficial for the tank.

Frequently Asked Questions About Aquarium Filters

Why do small aquariums need a fish tank filter?

No matter how large or small a fish tank is, the fish inside will always be producing waste. Using a filter helps maintain livable, healthy water conditions without you having to do water changes daily.

How often should you clean a fish tank filter?

Your filter should be cleaned out a minimum of once every 2 – 4 weeks. If it’s operating at the upper range of its abilities, clean it more frequently.

How do I properly clean my fish tank filter?

The main consideration with cleaning your tank filter is that you need to use tank water, not tap water, to clean the biological filter media. This helps make sure you don’t accidentally kill off the good bacteria with chlorine in tap water. Otherwise, you can safely clean your filter by any other non-chemical means.

What’s the best aquarium filter media?

I personally use Purigen (affiliate link). Although some of the other highly recommended filter media for fish tank filters include aquarium filter pads, sponges, ceramic, bio balls, foam, or gravel. Each type of aquarium requires a different type of media to be most successful.

Do all fish produce the same amount of waste?

Some fish are messier than others. This is something you need to know about before you finalize your setup. Cichlids and goldfish generally produce more waste than danios or neon tetras.

If your filter can barely handle the tank you have already, adding messier fish could render it ineffective. Messier fish need stronger filtration to maintain the same water levels.

Can I use a new aquarium filter immediately?

Yes, although biological filtration is a vital part of making sure water quality stays consistent. When you buy a new filter, it won’t contain the beneficial bacteria necessary for your tank, you can jump-start this process by using the media from an established tank.

For this reason, it’s recommended to let your new fish tank operate for a week or two before you put any fish into it, to let the filter build up beneficial bacteria. This is called “cycling”.

Conclusion

If you’re unsure where to start, the AquaClear Power Filter is a good one for beginners. It’s the best aquarium filter that’s great value for your money and will likely last you for a while. As long as it’s rated for your aquarium size, it’s a decent choice for most tank owners to try out.

Choosing the best aquarium filter is important for the livelihood of your whole tank. Understand what separates one tank from another and make the choice that best serves your specific tank and its inhabitants.