Best Canister Filter for Aquarium: Buyers Guide

If you have any aquarium, whether it’s freshwater or saltwater, its critical to keep the water as clean as possible. The way to achieve a healthy balance for your fish is to use a canister filter.

Canister filters handle all the chemical, biological, and mechanical filtration elements necessary to keep tank water free of debris and dirt particles that can harm your fish and look unsightly. You may wonder how to find the best canister filter for your aquarium, so I put together this buyer’s guide.

Inside, I explain:

  • What a canister filter is and why you need one
  • Types of canister filter media
  • The must-have features to look for
  • How to install and care for a canister filter

Of course I also include my top canister filter picks for both small and large tanks, to give you a jump-start on the best models on the market today.

By reading to the end, you’ll be able to confidently shop for and use the perfect canister filter for your aquarium!

What Is a Canister Filter?

There are two main types of filters for aquariums, a power filter, and a canister filter. The difference is that a power filter hangs from the tank and uses a tube to bring water in and out from the aquarium.

Canister filters sit outside of the tank, usually behind or below, and include more advanced systems and power to filter the water more thoroughly. Canister filters use a motor and pump along with inlet and outlet tubing that runs water to and from the filter.

Most canister filters have valves or other means to adjust water flow so that you can achieve the ideal level of filtration for the size of the tank. Once the water reaches the canister, it passes through each layer of filter media before the pump pushes the clean water back into the tank.

Why you need a canister filter

Less noise – Canister filters run more quietly and produce less vibration than other types of aquarium filters, so you don’t have to listen to annoying humming.

Higher flow rates – The amount of water filtration per hour is very high with a canister filter, which means you can turn over your tank water quicker, so the water stays cleaner.

Excellent filtration – Canister filters offer a superb level of filtration, so more dirt and debris get trapped inside, and your aquarium water remains much cleaner.

Easy to maintain – Canister filters are straightforward when it comes to disassembly for cleaning. By following the manufacturers’ instructions, you can open up the canister to clean internal components so you can have peace-of-mind the filter will continue to work.

Allows for versatile media selection – Canister filters come with a variety of media used for filtration so that you can choose the one most suitable for your aquarium setup.

Types of Canister Filter Media

There are three types of media put to use in canister filters:

  • Mechanical
  • Chemical
  • Biological

Each type of media can be bought in different forms like pads, strings or fiber, cylinders, or balls.

Most fish enthusiasts tailor the media in the filter to suit the particular needs of the fish and plant species in their aquarium. The way you layer the media within the canister is also important, as well as learning the do’s and dont’s of use.

Let’s take a quick peek at each type of media so you can better understand its purpose.

Mechanical media is the most crucial part of your canister filter system since it filters out large particulate that could choke the finer fibers found within the biological and chemical filter layers rendering them useless.

Mechanical media should always be the first layer within your canister filter. You can typically wash and reinstall mechanical media after a filter cleaning since the material is very durable.

Chemical media is most commonly some form of carbon pad that removes chemicals from the aquarium water that could harm your fish. Chemical media also works to absorb foul odors from your tank and clear up the water.

There are other forms of chemical media to use for specific tank issues, like ferric oxide for clearing out algae or phosphates in the water.

Sometimes experts recommend using little or no chemical media in your canister filter because it can also remove helpful bacteria and nutrients from the tank that some species of fish or plants rely on for good health.

Biological media’s sole purpose is to make a cozy home for the good bacteria your aquarium needs to remain in balance. As water flows through your canister filter, the biological media will capture and release these beneficial bacteria continually, so it mimics a more natural environment for your fish.

Best Canister Filters for Small Tanks

Some canister filters are more suitable for smaller tanks that do not require as much power to filter the water. My top picks below are for aquariums less than 150 gallons in size.

1. Penn Plax Aquarium Cascade Canister Filter

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The Penn Plax Cascade Canister Filter gets high ratings for keeping water super clear in tanks up to 65 gallons.

Type: Multi-stage
Flow rate: 185 gallons-per-hour
Size: 15″ tall x 11.5″ x 10″
Tank usage: Freshwater, saltwater

This filter features convenient rotating valves so you can position the hoses without extreme bends that could impede water flow. The push-button primer is another plus that makes initial setup and restarts after cleanings stress-free.

This unit comes with two large media baskets and enough media filter material to use the canister filter right out of the box.

On the downside, the hose quality could be better, and the gaps around the media baskets allow water to bypass through the system.

2. EHEIM Classic External Canister Filter

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The EHEIM Classic Canister Filter is a straightforward, easy-to-use system that delivers consistent results for aquariums up to 66 gallons.

Type: Biological, mechanical
Flow rate: 116 gallons-per-hour
Size: 14″ tall x 8″ x 6.3″
Tank usage: Freshwater, saltwater, turtles

The filter uses a Permo-elastic silicon sealing ring on the pump head that allows you to open and close the top after cleaning quickly. The seals and connections remain tight, which reduces chances for leaks.

The filter does not utilize filter baskets but holds loose media that you can layer in as you desire. No baskets do eliminate any chance of water bypass through the filtration layers because you can make sure there are no gaps.

On the downside, the lack of filter baskets makes it challenging to clean out the mechanical layer of the canister without having to dump out biological media you would rather keep undisturbed.

3. Fluval Advanced Filtration System

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The Fluval Advanced Filtration System may cost a pretty penny but provides outstanding filtration for tanks up to 80 gallons while also displaying flow rate and water temperature right on the digital display.

Type: Chemical, biological
Flow rate: 185 gallons-per-hour
Size: 10″ tall x 9″ x 10:
Tank usage: Freshwater, saltwater

This canister filter offers so many features like quick-disconnect hoses, an easy-prime system that automatically starts water flow, locking levers for complete seals, and a double-wall housing that eliminates noise from the motor.

The best part about this canister filter is that it alerts you when it needs cleaning or servicing. The compact design is another benefit, which makes it easier to find a place to tuck the filter system out of sight.

On the downside, the unit is expensive for use on smaller tanks, and the filtering media replacement price adds to the overall cost.

Best Canister Filters for Large Tanks

To handle the substantial flow-rate a big tank needs for sufficient filtration, you need a canister filter with a robust motor like these below.

1. Fluval Canister Filter FX6

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The Fluval FX6 Canister Filter provides powerful filtering and delivers consistent results for aquariums up to 400 gallons.

Type: Multi-stage
Flow rate: 925 gallons-per-hour
Size: 21″ tall by 15″ in diameter
Tank usage: Freshwater, saltwater, turtles

The self-starting filter is a breeze to set up, just fill with water, plug it in, and let the pump do the rest. Every 12 hours, the unit automatically evacuates any trapped air, so the unit runs smoothly.

The canister filter comes complete with mechanical, biological, and chemical media, which eliminates the need to purchase these items separately before installation. The internal media baskets stack, which helps reduce water bypassing the filters.

For safety, the canister utilizes microchips to monitor the pump operation to ensure continual optimal performance.

On the downside, you may need to regularly inspect hose connections and fittings to ensure they remain leak-free since they seem to weaken over time.

2. Hydor Professional External Canister Filter

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The Hydor Professional Canister Filter provides a complete eco-system for any aquarium up to 150 gallons.

Type: Mechanical, biological, chemical
Flow rate: 345 gallons-per-hour
Size: 24″ tall x 11″ x 9″
Tank usage: Freshwater, saltwater

The canister filter features an easy-priming system so you can get it up and running quickly after cleaning. The unit does a remarkable job filtering out even the smallest particulates, so your tank water looks clean and bright.

The filter operation is hushed, which reduces vibration within the tank and keeps your home peaceful. The materials are very durable and perform well, even after years of use, which makes this model cost-efficient.

For safety, the unit provides convenient shut-off valves to stop water flow when needed.

On the downside, if you’re not careful, you can easily overtighten the connector fittings, which may strip the threads and cause leaks.

3. Aquatop CF Series Canister Filter

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The Aquatop CF Series Canister Filter is a great choice for tanks up to 175 gallons because of its efficient filtration system and affordable price tag.

Type: Multi-stage, 4+1
Flow rate: 525 gallons-per-hour
Size: 18″ tall x 12″ x 11″
Tank usage: Freshwater, saltwater, turtles

Not only does this canister filter run exceptionally quietly, but it also features a UV sterilizer that kills bad bacteria and algae spores before they can overrun your aquarium and harm your fish.

The setup and instructions with this unit are clear and concise, which eliminates guesswork and frustration. When it’s time to clean and change out media, the process is just as simple.

On the downside, the o-rings that come with this system tend to deteriorate after several months of usage, which could cause leakage. I suggest you consider upgrading to better o-rings before the initial installation.

How to Install and Maintain a Canister Filter

Once you purchase a canister filter, you need to assemble it, install it, then maintain it, so it remains effective.

Read the manual that came with your particular unit, since different models may require specific steps others do not. After that, follow these basic steps to get your canister filter up and running.

1. Prep your aquarium
The first step is to find the correct position to place the canister. Ideally, the unit will sit lower than your tank water level, so find an out-of-the-way area on a table or floor near your aquarium. The manual should indicate what distance is best for maximum efficiency.

Fill the aquarium to its highest level, and direct the hoses in the shortest path to the tank. Avoid any twists or slack in the tubes, so you can check that they reach the tank and can function without issue.

2. Prepare the filter
Remove the motorhead of your filter canister and remove the media baskets. If your kit did not come with filter media, gather the media you bought and get ready to fill the baskets.

In the first tray, insert your mechanical media. Start at the bottom with a layer of coarse material, then follow it with a layer of fine and top it with an extra-fine layer.

Fill the second tray from the bottom next with the biological media.

The third (and sometimes fourth) tray is for chemical media like carbon or a phosphate remover or even some of each, whichever suits the needs of your aquarium best. Make sure you use filter bags for any loose media that could break apart and clog up internal motor parts like the impeller.

3. Prep the intake hose
The intake is the part of the filter that pulls water out of the tank. Each filter kit may have a different system, but most will include a connector that holds the hoses onto the tank.

Attach the connector where you want the hoses to enter the tank, then attach the other end of the hose to the filter canister at the intake connection. Now run the hose back up to your tank and secure it in the connector. Cut the tube off at the inside of your tank, making sure it sits at least three inches from the bottom of the tank.

4. Prep the output hose
Following the same process as the intake hose, set up the connector, attach the hose to the filter at the output connection, run the hose up to the tank, secure it, and then cut the hose so that the nozzle sits at minimum one inch under the waterline.

The output is clean water coming from the filter. Keeping the hose up higher in the tank will aid in circulation within the aquarium without being above the water, which will cause splashing and noise.

5. Start the filter
Always refer to the instruction manual first to see if your filter needs to have water in the canister before you turn it on. If they recommend it, fill the canister with water to the level they indicate.

After you close the canister back up, plug in the filter.

Some filters have an auto-prime feature, which will suck water in, then pause to expel air, then resume operation.

Some filters use a priming pump that you must push several times to get it working.

Once the canister is free of air, the filter should run continuously until you shut it off for aquarium or filter cleanings.

6. Maintain the filter
Canister filters are easy to maintain once it is up and running.

Check frequently for leaks at all connections, since o-ring deterioration or cracks in fittings could happen at any time, leaving your home flooded and fish gasping.

While many people only clean their canister filters every six months to a year, it’s best to clean them at least every three months.

The more often you clean the media, especially the mechanical layer, the more efficient your filter will run, and the clearer your tank water will remain.

Important Features to Look For When Shopping for a Canister Filter

Canister filters vary in terms of flow rate, number of filter baskets, and quality of hoses, fittings, and motor components. Look for these important features before choosing a filter, to ensure they meet your needs.


It is important to find a canister that will fit in your space, especially if you plan to hide it underneath your tank. Write down the measurements of the area you plan to set the filter and refer to it while shopping, so you don’t buy a unit that’s too large.


While you can find well-built canister filters at reasonable prices, sometimes less-expensive units rely on inferior materials to offer a low price.

Inspect the quality of the filter, check the thickness of plastic and hoses, and how well the fittings connect. Don’t settle for shoddy construction unless you want to have wet floors from leaks and cloudy water from poor filtration.


The motor in your canister filter needs to be powerful enough to pump water from the tank, through the many layers of filtration media, and back into your tank 24/7.

The only way to achieve this feat is to make sure the motor in your canister filter is robust and reliable. A poorly made motor will also run more loudly than higher-quality ones, so do your research and get the best motor you can afford.


Filters should have a rating that indicates which size of an aquarium it will work best.

The gallons-per-minute a canister can filter is an essential factor since the higher the number, the cleaner your water will be (as long as you maintain the filter media).

A smaller tank will not require a tremendous flow rate, since it may clear out everything beneficial from the water if it runs through the filter media too often. Follows recommendations for each brand of filter, so your tank stays in a healthy balance.

In Closing

Keeping the water in your fish tank as clear and clean as possible is the ultimate goal of a canister filter.

Now that you see the benefits of switching to a canister filtering system, you can use this guide to select the perfect canister system model for your large or small tank.

Once you have the best canister filter running in your aquarium, you’ll witness how much better your tank looks and feel great about improving the environment for your fish!

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