External Filters for Aquariums and Fish Tanks

Here you can directly access our reviews of the best external filters. But if you want to know everything about canister filters first, read on and we’ll tell you.

Hello dear reader, welcome to this special about the external aquarium filter.

The high range of aquarium filters
Customizable and versatile
Powerful and effective

The external or exterior filter, also known as a canister filter or basket filter, is the filtration device that is placed outside the tank.

This type of filter is not inserted into the water as is the case with the internal aquarium filter. It also doesn’t hang on the side of the tank like waterfall filters. It is usually placed under the aquarium, in the cabinet of the tank.

The use of the canister filter for fish tanks has become popular in recent times, more and more aquarists use them. This is because the canister filter has superior mechanical, chemical and biological filtration capabilities.

Above all, it is the most popular option among users with large aquariums, meaning aquariums of more than 150 liters. Although its popularity means that you can also find external filters for smaller aquariums.

Comparative table of the best canister filters

In this article we are going to tell you everything about external filters, and in addition, we carry out an in-depth analysis of the best external filters: Eheim Classic, fluval FX Eden Series.

These types of aquarium filters can be used for saltwater, freshwater tanks, reef tanks, or even turtle tanks and will work just fine.

This impressive compatibility is what makes outer filters highly appreciated by many hobbyists. In the opinion of a large majority of aquarium hobbyists, an external filter is a far superior way of filtering the water.

Best External Filters

Today there are many models of external filters for aquariums. From the old brands, new brands, some come with a UV sterilizer, others with specific filter media, etc.

Below, since it is impossible to choose the best aquarium external filter, we have highlighted some of the best brands and models of fish tank canister filter that are on the market today.

For each outer filter, we provide you with a brief overview, pros/cons, details, specifications, our review and conclusion.

fluval FX Series

fluval has launched the FX series of external filters for large aquariums. TheFX4for 1000 liter tanks and theFX6for 1500 liter aquariums. Two“beasts”of filtration for large aquariums.

Fluval FX works so that the hobbyist spends his time enjoying the aquarium, instead of having to do maintenance work. For this reason, these filters have some very interesting features such as the self-priming and automatic start function, or the Smart Pump technology.

It also has a multifunctional valve that is very practical when performing maintenance. It facilitates maintenance work and avoids disturbing the aquarium inhabitants.

Regarding filter loads, the FX series has a large capacity divided into multiple stages. In the Fluval FX4 there are 5 stages, and in the Fluval FX6 there are 6 stages. Both come with all the necessary filter media.

If you want to know more about these filtration “beasts”, in the following link, you can see our review of the fluval FX filter where we carry out a complete analysis of this series of external filters.

Eheim Classic

Eheim ‘s Classic filter series comprises a range of 5 models, ranging from 50-litre tanks to 1,500-litres. Its long history ensures a quality canister filter, as well as being simple.

These filters have a silent and smooth operation, with low consumption. And of course, the Eheim Classic filter series provides high-quality mechanical and biological filtration.

Eheim proudly boasts its million-time proven range of external filters of outstanding quality at affordable prices.

If you are interested in learning more about this series of external filters, you can go through our Eheim Classic review, where we see this range of external filtration systems in depth.

Eden 500 Series

The motor is completely sealed and thermally protected, which guarantees reliability and lower energy consumption.

The water is pumped through the internal multi-chamber filtration system, including a very effective biological stage that results in particularly crystal clear water.

The Eden range of external filters is a professional filter, suitable for both freshwater and saltwater tanks.

It is supplied with a complete intake system, hoses and connection elbows with a spray bar, which provides better oxygen exchange at the water surface or with a flow deflector to adjust the direction of the water.

The original design and its small size make placement next to or behind a tank very easy and safe, especially suitable for confined spaces.

Self-priming start-up via chamber filler cap, easy-open filter head reduces the risk of spilling water on the floor, and child-proof lock make these external filters more reliable than any other.

Vibration is minimal thanks to the four rubber feet at the bottom of the filter container, which also offer great stability and peace of mind, avoiding direct contact with the surfaces on which they are placed.

Lastly, this series of filters is available with an included aquarium heater. If you want to know more about this series of external filters, stop by our review of the Eden filter, where we tell you everything about this series.

Fluval 306

Building on the success of Fluval’s 05 Series filters, this filter provides improved functionality and filtration performance to provide the cleanest, healthiest aquariums.

The filter has a unique square design that holds 35-50% more water than similarly sized round filters, allowing better water flow through the complex cleaning path that maximizes contact with the filter media.

The Fluval 306 canister filter features a multi-stage filtration system that uses the entire volume of the canister to dramatically increase water flow efficiency.

Its mechanical stage features double-foam vertical prefilters to increase flow and reduce maintenance. The chemical and biological stages are housed in independent modules.

This means you can change filter media independently and ensure a constant level of the most important nitrifying bacteria.

Multiple modules allow for a wide range of filter media options for maximum versatility.

In addition, this external filter helps make aquarium maintenance as easy and hassle-free as possible thanks to a remarkable range of additional features.

Among these features, the patented Aqua-Stop valves stand out to facilitate the disconnection of the hoses, the hermetic closures, and the multiple removable filtration baskets that already come with the necessary loads for the filtration of the aquarium.

If you want to see a deeper analysis of this magnificent canister filter, go through our review of the Fluval 306 filter.

Hydor Professional

Let’s look at a few reasons why the Hydor Professional has earned its place among the best canister filters on the market.

It offers an outlet system with a spray bar that helps circulation and also oxygenation. And we already know that high levels of dissolved oxygen in the water support fish health, promote the growth of beneficial bacteria and reduce algae.

It has also gained a reputation for being very quiet, as cartridge filters have many advantages, but normally, noise is not included in many models.

Surprisingly, the Hydor Professional external filter is very close to silent. If noise is a big problem for you, you should consider this canister from Hydor.

It has a large water flow, every second that the pump is running, it circulates a large amount of water compared to many other canister filters.

This also means that more media can be added without sacrificing too much flow. In addition, the flow rate can be increased or decreased simply by adjusting the valve. Very convenient if your fish do not like a strong current.

The Hydor Professional comes with the necessary filter media and also offers plenty of space inside the tank for additional sponges, activated carbon bags or any other filter media.

We could continue telling you more about this magnificent external filtration device from the Hydor house, but for that we already have our review on Hydor Professional, where we analyze this canister in depth.

The canister filter for aquarium

As we said at the beginning, an external filter is the type of filter for an external aquarium, that is, it is placed in a place outside the tank. And today, as you can see on Amazon, there is a wide range of external fish tank filter models.

The basic system is very simple, it uses an inlet tube to extract the water from the fish tank. The water then flows through the filter media and to be pumped back into the aquarium.

Filter materials are normally kept in a pressurized container, hence some also use the name “canister filter” or “pressurized filter”.

The canister filter provides the best and most efficient filtration of the 3 types of water filtration: mechanical, chemical and biological. This is because most cartridge filters are pressurized, and the water is forced through a finer material to trap the smallest particles.

The external filter has the ability to filter much larger amounts of water than backpack filters. This is because the volume of the container is usually much larger than in a conventional backpack filter. This allows you to have more filter loads to achieve superior cleaning.

By the way, if you are interested, in the previous link you have the best offer on backpack filters. Also, we have some reviews of the best waterfall filters.

The downside is that most outdoor aquarium filters are much larger compared to other filters, and often have a higher price tag. It is best to try to consider it an investment.

It is best to do a little research before buying to make an informed purchase.

About external filter for aquarium

We are going to delve a little into the aquarium canister filter, seeing how it works, its main characteristics, advantages and frequently asked questions.

How does an external aquarium filter work?

Well, without going into too many technicalities, I will try to be as brief and concise as possible. Basically, the initial scheme is the same as any aquarium filter, with the addition of some hoses that allow the tank to be located outside.

It will have an intake hose to absorb the «dirty» water from the aquarium, and carry it to the container. Once the bowl of the external fish tank filter is filled with water, the internal pump will force it out of the device and into the tank.

Depending on the brand or model of canister filter, the direction of water flow within the canister can vary. It can be pumped from bottom to top, back to front, top to bottom, and out or in.

During this process, the water will pass through several layers of filtration within the container. The filter materials will trap all solid debris and other microorganisms, allowing only clean water to pass through.

Finally, after going through the different stages of mechanical and biological filtering, and chemical if necessary, the clean and purified water returns through another hose to the aquarium.

Logically, there is a need for regular maintenance of the aquarium external filter. The maintenance process is usually simple, since it is only necessary to disconnect the valves and open them.

The internal components must be cleaned according to the instructions given by the manufacturer. And use the same manual to reattach the components before reassembling the canister device into position.

Main characteristics of the external filter

High flow rate

When you compare an aquarium canister filter to another type of filtration system, it is easy to see that it has better flow rates in liters per hour. Some can even reach 1200 liters per hour. This means that the entire process of filtering your aquarium takes less time. Since it takes less time, it should also save you work and time.

If you’re shopping for a canister filter, just make sure you look at several models for their flow rates before deciding on one. Click on this link to compare different models on Amazon.

Large capacity of filter media

The fish tank external filter can hold much larger amounts of filter materials than the other types of filtration system.

These larger surface areas provide larger spaces for beneficial bacteria to grow. All of this allows for superior, higher quality filtration.

Powerful mechanical filtration

The primary goal of filtering your aquarium water is to remove toxic components from the water, and for that to happen you need to cycle the aquarium first. But we also want crystal clear water in addition to a healthy aquarium.

As the external aquarium bottle filter can hold more media, some special media is usually used that provides superior mechanical filtration. That means aquatic life will have a cleaner environment, and the aquarium will look crystal clear.

The filtration system needs to be cleaned periodically to ensure that it is working correctly and efficiently in the tank.

Media Flexibility

In addition to having more filter media, you can customize the types of materials you are going to use in your filter canister. If you want to remove certain chemicals or toxins, you can change the media to suit your needs.

The outer filter usually comes with several types of filter media that you can choose from. You just need to know how these means work before making the purchase.

You can read reviews on Amazon to see if they have always met the expectations of the owners. You can also check the amount of maintenance required for such media before you buy it. You probably don’t want to end up doing maintenance every few cycles.

easy to set up

The configuration of a canister is not complicated, it is considered as easy as any other type of filter. It is always important to follow the instructions provided by the manufacturer, you just have to make sure that the installation process is done correctly.

Most external fish tank filters are very easy to set up. Most require you to connect the tubes to the unit, add your media, prime it, and plug it in.

Even some outdoor filter units are self- priming, making the setup process almost non-existent.

The filter canister is very easy to clean.

Cleaning the external aquarium filter is easy when you have the manual and the necessary tools. Click here if you want to see different accessories that can make cleaning your external aquarium filter even easier. When it comes to an aquarium bottle filter, most come with parts that can be disassembled for easy cleaning of the internal components.

Manufacturer’s manuals are usually easy to read for trouble-free maintenance. Once it has been cleaned, the components are put back together to assemble it again, and it is ready to filter without losing any residue.


Any aquarium hobbyist prefers a filtration system that doesn’t make a lot of noise when it’s running. The best way to avoid noise and vibration is to use an external filter.

One of the main reasons why you don’t often hear the external fish tank filter is because it is usually kept in the closet. In addition, the design of the motor also plays a very important role, since most canister filters for aquariums are hermetically sealed so that you do not hear the impellers turning.

easy to hide

Because external aquarium filters are kept on the outside of your tank, you never see the filter itself. All you see are the inlet and outlet tubes.

This means there is more room in your tank for fish and plants. You can hide the device under your tank or in a closet.

Easy access

Because the filtration unit is located outside the tank, it is very easy to shut down, service and reconnect. And the best part is that it’s all done without disturbing the aquatic life in your tank.

multiple accessories

Most models of external aquarium filters have multiple accessories and accessories that will make your life easier. These aquarium accessories can be used in conjunction with your filtration system for even better filtration, ease of maintenance, or troubleshooting.

Accessories such as CO 2 Injection, Gravel Vacuums, Spray Bars, Chillers, Outflow Control , BIO -Wheels and UV Sterilizers can be used with most vessels.

Advantages of the External Filter

We have seen the main characteristics of this type of filtering system. Many of these are reasons to use an external filter. But there are two main benefits that make the filter canister the superior choice:

  • They add more volume of water to the tank. This means that it is easier to keep the water parameters stable, and much more difficult for toxins to build up quickly.
  • Greater filtering capacity. They can hold a large number of filter media, and can be customized to meet the needs of each aquarium.

In addition to these two main advantages, you also have more control over the flow of water, as well as the manner in which it returns to the tank. For example, the water inlet is usually located on one side of the aquarium while the outlet is on the other side.

This typical configuration of external filters ensures that the water is always circulating inside the aquarium. Instead, both the waterfall filter and the internal aquarium filter release the water very close to the device inlet.

This generates a more limited circulation inside the tank, and some areas of the tank can become stagnant. In the above link you have our special on the internal filter, in addition to several reviews of the best internal filters.

The external filter can be easily hidden from view with a wide variety of input/output devices available. They also require very little maintenance, they don’t need to be cleaned as often, maybe every 2-3 months.

How to choose an external filter for the aquarium

tank size

Not all external filters will be best for different tank sizes. Tank size is still an important factor to consider when looking for the best outdoor filter.

You have to read the description of the product and understand the size of the tank that can filter without problems. This will give you the necessary information to know which tanks will achieve the most optimal filtering for the model in question.

Filter Purpose

It is very important to consider the purpose when choosing a canister filter. This means that we must take into account the capabilities offered by the filter and the filtration needs of our aquarium.

You have to ask yourself if the canister will be enough for the volume, flow and versatility that your tank requires, among other needs.

It is best to get a filtration system that has the highest flow rate so that the filtration process takes the shortest possible time to complete.

The motor

The motors are important in helping to pump the water into the filter and start the filtration process. For this, it is important to have a good motor that pumps the water without problems.

The engine must also be reliable in terms of efficiency and maintenance. Some motors may need more maintenance than others, and having a filter that needs regular maintenance will mean you’ll have to open the unit more often. This is not always good for a canister filter.

The motor will also determine if the model can run quietly or if it will make a lot of noise.

Adaptability and durability

It is important to consider where the external filter will be located. For those who have a stand for their aquarium, they can simply hide it in one of the cabinets.

For a filter that is too high, you may have to look at other ways to keep it hidden.

When it comes to durability, look for a filter that is well-constructed so that it can ensure long-term service. Most are plastic, so make sure it’s a strong plastic for longer life.


Without a doubt, the brand plays an important role when it comes to buying an external filter whether it is for a small tank or a large tank. The brands seen in this guide are good and reputable at what they do.

When dealing with good brands we can always be sure that the products will work as advertised. If you prefer to go with other brands, be sure to do some research to see how their products work.


How to install an external aquarium filter?

As there is no universal fit for all external filters, u003cstrongu003eeach model comes with its own detailed instructionsu003c/strongu003e on how to do this. Don’t worry, it’s simple.u003cbru003eu003cbru003eIn general, u003cstrongu003emake sure all the parts are well assembledu003c/strongu003e and connect the inlet and outlet pipes. Connect the external filter to your tank according to the instructions of the device.u003cbru003eu003cbru003eSome use this trick that I explain below. Once you’ve assembled it and inserted the intake hose into the tank, plug it in. The vessel is now tilted sideways to submerge the impeller and start suction. You can hold it in this position for a minute and tilt it up to expel the air.

How is the configuration of the filter loads?

In general, you will find this configuration of filter loads:u003cbru003eu003cbru003eu003cstrongu003e- Ceramic tubes:u003c/strongu003e Its objective is to reduce the incoming inertia of the water and generate small currents. They can also host bacteria, there are even specific porous tubes for growing bacteria. bacteria. There are high-quality materials that achieve more than 400 mu003csupu003e2u003c/supu003e of surface area per liter. and change the perlon for a new one. REMEMBER, u003cstrongu003eALWAYS use water extracted from the aquariumu003c/strongu003e.

When should you clean the aquarium canister filter?

If you are wondering how often you have to clean the canister filter, I will tell you that as a general rule u003cstrongu003ese it is estimated that it is cleaned every 2-3 monthsu003c/strongu003e. Of course it depends on many factors, it can vary from one manufacturer to another and also how often it is used.

How to clean an external filter?

It does not differ much from cleaning another type of aquarium filter system, and consists of u003cstrongu003e cleaning the different filtering loadsu003c/strongu003e. If necessary, the different parts of the filter canister will also be cleaned, such as the pump rotor, the container or the hoses. In general, the passage leads are closed and the canister filter is disconnected from the hoses. The lid is removed to extract u003cstrongu003el filter materials and wash them with water from the aquarium itselfu003c/strongu003e. Remember that if you use running water, you will kill the colony of bacteria in your tank. First the biological material, which will be the least dirty. Then the mechanic, who will be the one with the most dirt.u003cbru003eu003cbru003eAfterward, it is recommended to clean the external filter container, the hoses and the different parts that make up the filtration system, such as the pump rotor.

Can I use it in salt water?

u003cstrongu003eYes. The vast majority of external filters for fish tanks are suitable when you want to set up a u003c/strongu003e marine aquarium, and you can see it in the description provided by the manufacturers. they would disagree. Muchos opinan que el filtro externo es una u003cemu003eu0022Fábrica de u003ca rel=u0022noreferrer noopeneru0022 href=u0022 target=u0022_blanku0022 class=u0022rank-math-linku0022u003eNitratosu003c/au003eu0022u003c/emu003e o que u003cemu003eu0022no es adecuado para salt waterau0022u003c/emu003e.u003cbru003eu003cbru003eOthers think this problem is caused by not providing enough water changes. The filter canister is an excellent mechanical filtering system, it improves circulation, and allows a higher quality chemical filtration. And ammonia and nitrogen are produced from fish waste and uneaten food. Therefore, it is simply the result of a lack of water changes.

Conclusion on the Canister Filter

The efficiency of the canister filter in purifying the aquarium water is difficult to match with another type of filter. The characteristics of this type of filtration system allow it to provide superior filtration while requiring less maintenance.

Whichever way you look at it, the outer filter is better in every way. There are many advantages that it has, and although the price seems to be a problem, you quickly realize that they are worth more than they cost.

Just think that under normal conditions, a filter canister needs cleaning and maintenance every 3 months. It is an investment in the health of the aquarium and in your time.

In short: If you want health in your aquarium, an external filter. If you want crystal clear water in your tank, a canister filter. If you would like to forget about cleaning the filter system for months, an external filter. If you want…

Publicaciones relacionadas

Deja una respuesta

Tu dirección de correo electrónico no será publicada. Los campos obligatorios están marcados con *

Botón volver arriba