Canister filters for freshwater and saltwater aquariums

So, you are choosing the canister filter? The most important fact you should know is that their manufacturers quite often play hanky-panky with you when indicating the amount of water being pumped by a filter per hour. So, in this respect you should buy a bit oversized model. And this is it, now you may skip the rest of the article since below there are only boring details and comparisons, characteristics and IMHO as for studied models.

However, if you are interested you are welcome to continue reading… In general, I’ve listed all worthy models and if there are others, then they are made by some noname brands, or they are some rare models, to describe which I haven’t found sufficient amount of information.

Best canister filters in 2021

Penn Plax Cascade

Penn-Plax Company is a popular American manufacturer of cheap goods for aquariums. Filters produced by Penn-Plax are manufactured in China, however they are rather good quality ones.

Penn Plax product line is represented by canister filters for marine and freshwater tanks from 30 US gallons to 200 US gallons.

Company was established in 1960 and it has been producing equipment for aquarium husbandry, terrariums and other pets for over 50 years already.

Thus canister filter is for aquariums up to 100 gallons and pumps 265 gallons per hour (GPH). There are two trays with foam in each one and also charcoal in one and course media in the other. The filter is equipped with a spray bar.


  • It’s equipped with a spray bar
  • It has a button for water injection that eases the filter priming
  • Price is very low when comparing to other branch
  • You can put different media into the large trays with handlers that can be put on top of one another
  • Very quiet operation
  • Fast and easy hoses detaching for maintenance
  • Super easy to setup
  • Easy to clean


  • Just like all other companies this one also states the filter output value to be larger than it is in fact
  • Pipes are made of fragile plastic
  • It’s hard to prime
  • Cheap filter media and cheap baskets
  • The carrying handle is very flimsy
  • Written instructions and pictures are simply not accurate

Hydor Professional

Hydor company (the Italian one, not Chinese) has entered market relatively recently.

It had Hydor products line and now professional model has come to substitute it. The new product line consists of 5 models (for tanks from 20 to 150 gallons); they have different pump output which allows choosing a model required just for your tank.

Canister is made of sturdy plastic, it has rectangular cross-section which lets you easily put it in the corner of your tank stand.

The canister clamps have a system that prevents their self-opening and thus ensures leakproofness and reliability of the tank filter. All media and fillers come in the set.

Each component is in separate basket which allows taking out each of them easily from the canister to wash or replace.

Tight baskets arrangement in the canister provides good water flow directly through the media, which prevents clean and dirty water mixing inside.


  • It is good for marine and freshwater tanks
  • Ceramic axle ensures failure free operation
  • It has universal large volume baskets
  • The maintenance is performed fast and easy, the hoses can be easily detached
  • Due to the reliable clamps and special o ring any leakage is prevented
  • The filter is supplied with all necessary fillers excluding carbon
  • It has a sectional spray bar that consists of several sections
  • Wide, conveniently fixed hoses
  • Easy assembling and fast filling with water
  • Quiet operation
  • Very large priming button
  • Extensible tubes
  • Large internal volume


  • It doesn’t have any spare parts, so if something gets broken when out of warranty it’ll be difficult to find a replacement
  • It’s desirable to buy some more media, since the filter doesn’t have rather wide range of it by default
  • The filters are brought from far, so sometimes they come with damages because of this
  • Not the best quality plastic is used

Fluval Fx6 and Fx4

This filter is made for tanks with large amounts of organics that has to be removed mechanically. These are large tanks with plants or with large fish.

The filter has an electronic circuit that continuously controls its operation. Impeller spin speed and rolling force are measured continuously to ensure the filter output and efficiency.

The circuit also provides the filter autorun and removes the air which can accumulate inside the system. Once in 12 hours the pump stops and lets the accumulated air out of the system ensuring by this the efficiency at any moment of time.

All new product produced by the company in 2016 is Fluval FX4 which has some improvements comparing to the previous model.

A new highly-efficient Fluval FX4 for both marine and freshwater tanks up to 250 Gal. This filter has 5 stages of water purification; capacity is 30 Wt, circulation is (450 US Gal) per hour. Unlike its precessor FX4 has become more compact sized and it doesn’t take much space now.

A new smart-pump has been designed for Fluval FX4, which provides the maximum output. The pump has a special electric circuit inside which completely controls its operation.

All details were thoughtfully chosen. The filter consists of 4 containers with total filtration volume (14L or 3/7 US Gal) and biological volume 3.9 L (1 US Gal).

Baskets come in order in such a way that it provides maximum efficiency and crystal clear water in a tank. Filtering medium and fillers are put in several layers so the water when coming through the filter gets maximally clean from dirt, garbage and harmful microorganisms.

The baskets with fillers have subsidiary sponge on the edges which performs additional mechanical water purification. Each basket is responsible for efficient water filtration; foam performs mechanical, preliminary water purification by capturing the smallest garbage particles.

Fluval FX4 has a special handler by means of which you can take out and separate all baskets easy and fast.

Such an improvement was designed to simplify maximally the maintenance. Now you don’t have to waste time disassembling completely to wash the fillers.

There is an indicator on top of the filter which helps you to remember the date of the last maintenance.


  • Large volume
  • Large amount of media
  • Monthly maintenance indicator allows remembering the date of the last technical service and water renew
  • Pump undermount
  • System with drain hose which allows to drain water and fill with it without disassemble ing the system
  • It will do both for freshwater and marine tanks
  • Autorun function
  • “Click-Fit AquaStop” taps ensure fast and reliable maintain


  • Bottom pump may get clogged with sand and then jam
  • Is made for mechanical filtration and the biological one takes a backseat
  • Rather expensive
  • Not maintenance friendly

Aqueon QuietFlow

Conventional market of canister filters changes quite seldom and new models appear there rather rarely. Chinese brands make the only exception in this respect, but I’m not sure if we can actually call them new since even their brands are very much alike.

So, Aqueon QuietFlow is a true new model. Though it has a few reviews, it seems to have good prospects. It doesn’t have an adaptor like other models. To open the filter you have to shut off two taps on hoses in front of the filter input, release the hoses and take of the cap.

The taps are of rather high quality, they don’t leak and they are rationally placed, so when releasing them water doesn’t spill from them.

Three baskets with materials contain carbon, coarse foam, bio balls and bio-ceramic rings. Small number of baskets is offset by their size; each basket is quite large and contains large number of materials.

A new and unusual approach was used when designing this filter – it has HOB polisher, which is installed on the back side of the tank. It contains an additional carbon filter for chemical purification of the tank water. When its cartridge becomes dirty, it can be easily replaced.

Priming can be a bit difficult to figure out at first, the easiest way is to use the HOB polishing unit, and just pour water into it until it’s full.


  • Its price
  • Very quiet
  • The easiest to prime


  • You have to read the manual

EHEIM Classic

Eheim has been producing filters and tank equipment for many years already. The company manufactures sustainable, maintenance-friendly and efficient products.

These filters can be used in any tank, they are plain and sustainable. If you don’t want to get into details and just to buy and turn it on, this is the one you need.

Its drawbacks are that it comes short of filtration rate and some other abilities when comparing to more modern models and you’ll have to buy media for it.

This is proved by company’s 50 years experience of filtration systems creation as well as by many years experience of their utilization by aquarists. For the majority of aquarists Eheim means quality and security.

Despite the fact that «Classic» filters product line has been on the market since 80s it has filters justly called a “willing horse”, some of them have been used for almost 20 years.

Here is the filter with the simplest design. It can be considered as a straight pipe filled with media.

Filter media can be placed both directly in its canister and is a special cassette made for it. When installing the cassette you should push it down harsh but slightly till it is fixed in its lowermost position.

This ensures reliable pressurization between the cassette and the case; it excludes ingress of not filtered water back to the tank as well.


  • It can be used in any tank
  • The quality has been proved by years of their usage
  • Several such filters can be used in a big tank
  • Small internal volume is compensated by its maximum efficiency
  • Very low power consumption
  • Reliable ceramic axel and bearing part


  • Some models sets have only sponges without fillers
  • Some models don’t have double taps
  • Small internal volume
  • Old-fashioned design
  • Manual prime
  • Rather fragile plastic
  • Filter set doesn’t have any means to simplify the priming or maintenance and there is no starting bacterial culture

Fluval 406

Here is the third product line of filters Fluval 106, 206, 306 and 406 they are for those, who want just a simple filter without any frills.

Fluval 406 flow rate: 1450 L/H (383 US GPH) – this is a legendary canister filter of the 6th generation from Hagen. This filter is for optimal water filtering in freshwater or marine tanks up to 400 liters (100 U.S. gallons).

Provides 3 stage full biological, mechanical and chemical water purification.


  • Its engine can provide strong water flow through media
  • Unique design ensures multi-stage filtration
  • Almost any media can be used for 06 model
  • Aquastop system prevents water leakage since it turns the filter off once the hoses detach
  • By means of the new clamps you can easily create a filter and reliably fix the engine
  • Due to the fact that the sponges are easily accessible it’s not a problem to replace the filler
  • Using fast start system it’s simple and easy to prime
  • 3 years warranty


  • Canister small capacity
  • Small amount and confusing set of medium (you’ll have to buy some yourself and replace them)
  • Only branded sponges can be used
  • Very small amount of ceramic filler in a set
  • Canister plastic is very thin
  • Fast start system is rather simply
  • Rotor ceramic axel is thin
  • Rotor blades are also quite thin
  • It has only two clamps
  • The baskets are rather small and thin

Fluval G6

Fluval G6 will do for those who are keen on technologies, for whom their appearance is an important part of interior environment and also for those, who love marine aquariums.

This is an innovative, highly-efficient and quiet external filter of G-series, which ensures three stage filtration of tank water and this is an ideal choice for marine and freshwater tanks.

It was stated that despite the small output the filter can easily deal with a tank up to 600 liters, however in the real life you should halve this number.

The filter rate is 265 gallons per hour. The main innovation in Fluval G6 – is «Hydrotech Performance Monitor» module – a set of sensors that measure temperature, flow rate and conductivity.

As well as a processor unit with display that ensures both managing data of current measurements and then gather data and output it onto interactive LCD-display. Fluval G6 monitor allows controlling temperature, water flow rate and conductivity, and it displays all these parameters as numbers and graphs.

The software continuously monitors the functioning and in case of emergency displays the warning message ALERT. The monitoring system also reminds its owner to the perform maintenance service when it is necessary.


  • Stylish design lets you put the filter as a part of interior environment; you don’t have to hide it somewhere
  • Maintenance friendly
  • Embedded software to control the main parameters
  • Very quiet in operation
  • There is no statistics and setup data loss when the filter turns off
  • The following data is displayed: temperature, water flow rate (if it gets low an alert appears that the filter requires washing), the display shows water electrolytic conductivity (when this value rises it’s a signal to renew the water)
  • For marine tanks it displays salinity degree
  • Quality fillers
  • Easy to clean – you don’t have to open the lid completely
  • Well equipped
  • Not very high
  • It will do well for marine tanks


  • The price
  • Expendables are to be bought and replaced regularly
  • Expendables price
  • It won’t do for tanks with large fish, since you’ll have to replace expendables very often
  • The media gets clogged very fast and they have to be replaced
  • A bit confusing fast start system

AquaTop Forza

AquaTop company (China) produces one of the simplest and cheapest filters among all of the presented models.

The company has rather wide product line, but all filters have common characteristics and list of equipment. These filters are in great demand, since quite often price plays a crucial part. But are they really as cheap as they seem?

Let’s find out.

For example, let’s consider AquaTop Forza with embedded UV-sterilizer for tanks up to 175 gallons and pump output 550 gph.

UV-sterilizer power capacity is 13 W and it provides crystal clear tank water preventing appearance of green algae, different microorganisms and pathogenic bacteria in a tank.

So, you can turn of your UV lamp. The filter has high quality ceramic axel to ensure its noiseless operation. There are 4 baskets for different media – biological, mechanical and chemical one.

UV plus expendables…. However, in fact all of them are of rather low quality and their amount isn’t enough for the filter to function efficiently.


  • The model has UV sterilizer, though it’s not powerful enough to operate efficiently
  • The sterilizer comes first and all tank dirt will be accumulated on it, since it has to be placed after filtration
  • Rather low price (there are no analogous filters with the same parameters and the same price)
  • Very noiseless in operation
  • It has a pump for priming


  • Rather fragile plastic
  • No spare parts
  • White color is very easily soiled
  • Poor engine performance
  • Short hoses


API Company (USA) has been on tank equipment market for over 50 years already and it has a good name.

But are its canister filters good, especially if before they were produced by Rena? Since the time when Rena was bought out by API some rebranding has been introduced.

The company has a product line API FilStar XP. Here after XP the model is indicated according to its output.


  • 2 years warranty
  • Very quiet
  • Large internal volume
  • Good quality filter media
  • Easy priming
  • No extra charges for the brand


  • It has no spray bar
  • More frequent complaints about leakages
  • Low popularity at

Cobalt Aquatics EXT

The filter is good for those who don’t have the ability to put a filter under a tank.

This filter’s feature is that it doesn’t need priming and it can be put below, next to and even above the tank! Since it just doesn’t have a pump in its head, the pump is put into the tank together with the intake pipe.

This allows switching of the filter and washing it without turning the pump off. I.e. you turn the latch handle, take away the canister and the pump continues working.

Max flow rate is 210 gph (800l), the filter is for tanks up to 55 gallons, total canister volume is 1.85 gals.


  • Unusual, even unique technical decision
  • Very low price
  • Ability to maintain without switching it of
  • No need in priming
  • Canister itself is very sturdy
  • Location of the pump outside the canister allows increasing its effective volume
  • Three years warranty
  • Quiet
  • Quick disconnection of valves which allows the water to keep flowing
  • Tons of included media
  • The box is designed to have little or no bypass.


  • There is only one model in the product line – just for tanks up to 55 gallons
  • The pump on the intake pipe consumes additional space in a tank and it’s far more noticeable than a common pipe
  • Cheap accessories
  • External pump adds more complexity to the setup
  • The included plumbing kit is unusable
  • No spray bar. This type of filter system generally works better with spray bar to help break surface tension and provide the water with oxygen exchange. Without something in an aquarium to provide this function the fish will suffocate and die.
  • The intake screen doesn’t fit any of the tubing adapters and will barely stay connected to the pump. For internal pump configurations the screen needs something to affix it to the pump. For external pump configurations you are pretty much screwed.
  • Polishing floss is just an unruly mass of loose fluff

FAQ – How to pick a canister filter?

The most important advise – don’t try to find an ideal model. If you read canister filters reviews in forums – they’ll drive you crazy. One and the same model is being blessed and cursed at the same time.

The story is the same for all filters without any exception.The rule here is simple – the cheaper the model is, the less you should expect from it. However, you may get the short straw with an expensive one and it may be a rejected product.

Though, the expensive ones usually have a good warranty.

All filters are divided according to their pumping rate (how much water do they pump per hour). And here, almost all the manufacturers are not quite honest, since the pumping rate indicated by them can be obtained only when the filter is “empty” – without any media or when the filter is clean. As far as the filter gets clogged its pumping rate decreases.

You should buy double or triple oversized model. So, if you have 50 gallons tank, then buy a filter optimized for 100-150 gallons.

There is no filter, that makes water renews unnecessary! Regular water renew is a must with or without a filter.

Which type of filter is best for aquarium? If you doubt which filter to buy – keep in mind, that canister filters are always better. They are multi-fold efficient, since apart from mechanical water purification they provide biological and chemical filtration.

Are canister filters good for saltwater tanks? Sure, most of them.

The wider the hoses are the more efficient the filter is. Its pumping rate is defined by the width of the narrowest section of the hose.

Canister filter requires the simplest fillers in small amounts. You’d like to improve water filtration efficiency sufficiently? Then buy the fillers. Due to these expenses cheap filters become not as cheap as they seem.

There are no multipurpose filters. You’ll have to select a filter for each task you have in mind. For example, for a tank with cichlids and for a planted tank you’ll need completely different filters.

If you doubt as for the pumping rate – always buy the more powerful one. A powerful pump may be needless only in very small tanks.

For successful operation a filter should be placed below the water level and usually it is placed under the tank.

Avoid the hose kinks! This is crucially important since when in service these kinks may get clogged and lead to pressure increase in the system and to further hose detachment from the filter.

Sealing rubber o rings should be greased with a special silicone or vaseline and then they serve longer.

Pay attention to the clamps. They should at least look sustainable. Simply looking clamps are the reason for the leakages.

The way the hoses are fixed to the filter intake and output pipes. Fixation should be sustainable by means of hold-down nuts otherwise the hose can just jump out of the pipe, since it becomes more flexible in time.

Some models have a trouble spot – so called adaptor. It has to detach the hoses fast from the filter and simultaneously block the water flow. It’s a quite useful device, which largely eases the filter shut down for maintenance. But in some models adaptor starts leaking because of its o rings wear or some mechanical damage.

Pay attention to the pump impeller axle: it may be a metal one (more cheap) and a ceramic one (more expensive, which is good for marine tanks). The ceramic axle is considered to be more wear proof and less noisy, however it’s rather fragile and expensive in case of replacement.

The majority of filters come already fully equipped with everything that is necessary: sponges of different porosity, ceramic pellets, bio-balls, absorbent carbon.

However, some models are equipped only with sponges.

How to find best canister filter?

I assume you’re quite busy guys and you don’t have time to read all of this and enter into all the details.

Well, me either.

There is a rather wide range of external filter brands and there are much more filter models on the market. What is confusing that famous and old brands have a lot of different filter models – easy in care and cheap ones, expensive and sophisticated ones.

If you want to buy a filter for your tank and you see one or three models provided by the brand, it means that the company isn’t focused on filter production or maybe it has just entered the marked.

In my opinion company’s specialization is important since it is a determinative factor and those who produce lots of stuff in small amounts loose to those who are focused on production of just one product.

So what is it exactly – biological, mechanical and chemical filtration?

Biological filtration, i.e byproducts transformation in a tank. This involves deactivation of ammonia and ammonium which are toxic for tank inhabitants and transferring them into less harmful nitrates that in turn are partially recycled by tank plants and partially removed when performing water renews.

Biofiltration is performed by nitrifying bacteria that inhabit in a filter.

Technically speaking any filter is more or less occupied by nitrifying bacteria and it can be called a biological one. The thing is that biofiltration is just more efficient in filters of larger volume than in smaller ones.

Mechanical filtration or cleaning the water of organic or inorganic suspended matter.

Many people consider that this is the main purpose of any filter. Of course it’s not very nice to see muddy tank water.

However, the main operating result of a filter is still an efficient biofiltration, not just cleaning tank water of suspended matter and mud. In case of well arranged biofiltration process the tank water is crystal clear.

Chemical filtration is based on filter medium and tank water interaction that changes the water properties or content of some matters in the water.

Ionite, zeolite and other substances are used as a filter medium.

Adsorbtion of some substances (for example some medicines after the treatment was finished) this is when carbon is used.

The larger is a ratio of filter media to a tank volume the more efficient filtration is. It’s rather difficult to put a large filter in a tank, since it’ll take additional effective volume.

Such internal filters are the best for small or sparsely populated tanks. In the rest of cases an external filter should be chosen.