Types of filters for fish tanks

In the market you can find a wide variety of types of filters for fish tanks and aquariums. Each type has its advantages and disadvantages, so in the end the filtering strategy that you want to use is a “personal” decision.

If before knowing the different types of filters there are, you want to know how a fish tank filter works, we will explain in this article the basic operation of a filtration system.

You may also be interested in knowing the types of filtration that occur in a filtration device. We also have an article in which we explain it to you.

Firstly you will be able to differentiate between internal and external. And within these categories, a wide range of options that you can find in the market.

Internal Fish Tank Filters

See the Best Internal Filters for aquariums

If you want to know which are the best internal filters for fish tanks and aquariums, we have a comparison guide to help you find the best submersible filter system for your tank.

It is also common to use it as a support filter, providing extra filtration. It is placed inside the aquarium attached to the glass with suction cups and usually consists of a sponge as a mechanical and biological filter material.

Internal fish tank filters are typical of kits and do not usually have much filtering capacity. It occupies space inside the aquarium, which is also not very aesthetic.

The types of internal filters for aquariums offer the following varieties of application:

  • Vertical or horizontal placement.
  • Extra filtering in different aquarium systems.
  • Creation of additional currents.
  • They activate ultraviolet sterilizers.
  • They are the solution when external aquarium filters cannot be used.

The placement of the filters for internal aquariums must be in such a way that the exit of the filtered water causes movement on the surface.

This movement of the water surface favors the exchange of gases with the air, improving the concentration of oxygen in the aquarium.

If you want to know more about the types of internal or submersible filters, go through our special article on the internal filter for fish tanks. There we see the most valued internal filter models, frequently asked questions, the main characteristics, technical data, assembly, cleaning… everything about the internal filter.

Advantages and disadvantages of the internal fish tank filter

  1. They are easy to use and maintain.
  2. Are cheap.
  3. They have different applications.
  1. The filtering capacity is quite low.
  2. They occupy space inside the aquarium.
  3. It is in sight.

Aquarium Sponge Filter

The water passes through the pores of the sponge filter through the use of an air pump or a power head. A mechanical cleaning is carried out in addition to allowing the establishment of a large colony of friendly bacteria.

There are models of sponge fish tank filters for aquariums that come with two sponges. This allows cleaning only one at a time, thus reducing the loss of the bacterial colony.

You should also place it in such a way that the clean water outlet causes movement on the surface of the water. This will favor the oxygenation of the water.

Pup Filter

There is also the Breeding Filter, used in breeding aquariums because its suction power is very small. Very useful for quarantine aquariums due to its great oxygenation. There are two types, sponge and box.

Corner Filter

It uses a pump to pass the water through the filter load. The filter material must be partially washed so as not to lose its bacterial colony.

These types of aquarium filters are used in small tanks, and their efficiency is quite limited.

Like the rest of internal filters, corner type aquarium filters are not very aesthetic either. It also takes up space and needs more maintenance.

Plate or bottom filter

The aquarium plate filter is a plastic plate with small slots that occupies the entire bottom of the aquarium connected to one or more tubes that come out in the form of a chimney. They are placed under the gravel, and it is the gravel itself that serves as the filter medium.

The water is sucked through the gravel, thanks to an air pump or «power head», and returned to the aquarium through the plastic tube. Click on this link to see the background filters that are on offer in the Amazon showcase.

These types of fish tank filters work as excellent biological filters that host the colony of nitrifying bacteria. But also as a mechanical filter, since all the solid waste is trapped in the gravel. The problem is cleaning, which is much more cumbersome.

Periodic cleaning is required to remove solid residue build-up in the gravel. It is known as siphoning the gravel, and it is essential with this type of filter.

One technique used to minimize this mishap is to reverse the pump, sending the water through the gravel, and placing a sponge at the pump inlet to remove solid debris.

If you decide on this type of filter for internal aquariums, you will need a siphon to carry out periodic cleaning of the bottom.

This system is very economical and effective, so it is widely used as a filter for freshwater fish tanks in tropical aquariums, and also in sparsely populated marine aquariums.

Inverse Plate Or Bottom Filter

It is the same filter model as the previous one, differing in the direction of the water flow. In this case the water passes from the bottom plate, through the gravel, to the aquarium.

Normally, an external aquarium filter is used, such as a canister or a «head power» connected to one of the plate tubes to achieve reverse circulation of the water.

I recommend that the water that passes through the bottom plate filter be previously filtered to avoid residue accumulation.

If you opt for this type of filter, it is also necessary to siphon the gravel regularly.

External Aquarium Filters

This type of filtering is based on the use of a siphon that carries the water through various filtering materials and then returns it clean through the outlet flow. Although there are different configurations of external filter systems, they must filter mechanically, biologically and chemically.

We are going to see the main types of external filters that are used in the aquarium hobby. The most popular are backpack and canister, but there are more types of external filter devices.

Cascade Or Backpack Filter

See the Best Cascade Filters for aquarium

If you want to know which are the best backpack filters for fish tanks and aquariums, we have a comparison guide to help you find the best waterfall filter system for your tank.

Backpack types of aquarium filters allow for a higher capacity for filter media, thus allowing for more versatile and efficient filtration.

Ideally, in addition to the sponge, there is some porous material for the biological filter. Some also recommend a layer of Perlon.

There are many models, but the most common hangs from the rear glass of the aquarium, so it is still visible, but does not take up space inside the aquarium.

Through a tube or rubber, they suck the water from the aquarium, pass it through the different filter materials for aquariums and return it clean.

There are several types of this model of fish tank filters:

  • Cartridge design.
  • With a compartment to place the filter materials.
  • Others have so-called » bio wheels «, which are a paper tube made up of sheets. The cylinder rotates by the flow of water offering extra oxygenation and an ideal place for the development of the biological filter.

When it comes to maintenance, you can deep clean the sponge if you have another burden for the bacteria colony. This porous load for bacteria rinse it a little. Do not forget that ALWAYS with aquarium water.

If you are interested in waterfall type fish tank filters, you can take a look at our article dedicated to the backpack aquarium filter.

Advantages and disadvantages of the internal fish tank filter

  1. They do not need hoses, therefore there is no danger of leaks.
  2. Filter media are easy to change and clean.
  3. Cheaper than an external filter.
  4. There are no disturbances in the optics of the aquarium.
  5. Relatively free choice of filter media.
  6. Mulm and other filtered particles do not re-enter the aquarium when removed for cleaning, as is the case with many internal filters.
  7. The volume of the filter can be increased very easily and effectively by placing a filter cartridge over the water inlet.
  1. Flow direction and surface movement cannot be specifically adjusted on all models.
  2. Due to the strong movement of the surface it generally expels a little more CO2 than an internal or external filter. Therefore, the CO2 supply must be slightly increased.
  3. Relatively high purchase price compared to the internal filter.
  4. Not suitable for all aquariums, difficulties for example in aquariums with lids and aquariums with lids or rims.
  5. A smaller filter volume than a “real” external filter.
  6. A smaller filter volume than a “real” external filter.
  7. The inlet and outlet are in the same place, so large tanks don’t flow properly.
  8. A filter hanging on the outside of the aquarium can be visually distracting.

cylinder external filter

See the Best External Filters for aquarium

If you want to know which are the best canister filters for fish tanks and aquariums, we have a comparative guide to help you find the best external filter system for your tank.

They are normally used in medium and large sized aquariums. The external filter or canister is made up of an independent tank with two hoses. A hose that sucks the «dirty» water from the aquarium, and another that returns the clean water.

Maintenance of these totally external systems is the easiest and most comfortable of all types of aquarium filters.

External aquarium filters, also called aquarium basket filters or Canister, or pressurized filters have many advantages:

  • Large capacity for filter material.
  • Greater variety of filter materials.
  • They are more efficient.
  • Longer contact time of the filter with the water.
  • They do not take up space inside the aquarium.
  • It is more flexible when it comes to location.
  • They are quite easy to maintain.
  • Allows more time between maintenance.
  • Their biological capacity is greater, being able to take charge of larger fish populations.
  • It is easy to connect with additional water filtration and treatment devices, such as skimmers.

But it also has some drawbacks: the external filter or canister is more expensive and takes up additional space on the outside.

To facilitate the efficiency of the filter material, it is advisable to choose a design that maximizes the contact time with the filter.

Settlement Filter

There are simple and multi-chamber ones, and they can also be internal or external.


We can include this type of filter within the settling filters.

This filter is an extra container that consists of several chambers, widely used in marine aquariums. There are endless configurations of shapes and methods of this type of fish tank filter.

As it is an extra tank, it increases the amount of water in the aquarium, and allows it to house all the technical equipment, preventing it from taking up space in the aquarium. Click on this link to see one of the best-selling sump-type aquarium filters on Amazon.

  1. Get more volume of water.
  2. Hide all the accessories.
  3. Improves stability in the pH level.
  4. Promotes water circulation and oxygenation.
  5. Facilitates and improves regular maintenance.
  6. Helps the growth of macro-algae.
  7. It favors the cleaning of the water surface.

Wet Dry Filter

They are based on providing a medium rich in oxygen to favor the establishment of a large colony of beneficial bacteria. It is one of the most efficient types of biological filters for aquariums.

Click on this link to see Amazon ‘s offer on this type of filter for aquariums.

The key to these aquarium filters is to have large contact areas and large openings for efficient gas exchange. In this filter, the bacteria take oxygen from the air and not from the water.

Commonly this type of filter is made up of different tanks with different filter materials in the following configuration:

  1. 1. First, the water passes through several mechanical filters.
  2. 2. Then it reaches a settling tank.
  3. 3. It ends up dripping on the biological filter material.

The biological load used in these types of filters are usually bioballs, which are specific hollow plastic balls to favor the development of the bacteria colony.

The disadvantage of this filter is that it takes up more space and generates more evaporation.

This type of filter for aquariums needs more control and cleaning than other filter systems, so I do NOT recommend it for beginners.

Tile Filter

The tile filter is similar to the dry-wet filter in operation. It is placed in the upper part of the aquarium, and with a pump the water passes through the filters and falls into the tank as rain.

Protein Skimmer

Technically an aquarium protein skimmer is not a filter or a filtration system. It is actually a device that prevents, avoids the formation of toxic compounds.

Also called urea skimmers or separators, they were developed for industrial waste treatment plants, and the key to these devices is that they remove organic remains before they decompose.

These accessories are used in Marine Aquariums as complements to the filtration system: filtration and skimmer

They are based on the production of certain bubbles that, when rising to the surface, trap proteins before they are transformed into toxic compounds.

On the surface of the water, the bubbles end up forming a foam that retains all these proteins, and ends up in the overflow glass, outside the aquarium circuit.

With this complement we also manage to improve oxygenation and the relationship between additions and losses of oxygen in the chemical processes of the aquarium (Redox Potential).

Fluid Bed Filter

Fluid bed types of fish tank filters consist of a container filled with sand that serves only as a biological filter.

When crossing the water, the sand produces a movement in it that generates a great oxygenation and development of the bacterial colony.

Its great advantage is that it is a very efficient biological filter for its small size.

It requires a high efficiency pre-filter to keep it very clean.

Algae Filter

The algae filter or algal scrubbers for aquariums use live algae to carry out the filtering. This biological filtration system is used in fish farms and to control eutrophication in rivers and lakes.

The key is to have a suitable place for the development of microalgae. Water flowing over a plastic screen under adequate lighting is ideal for «growing» beneficial algae.

Within a few weeks algae begin to appear on the mesh, and as they grow they will remove more and more of the nutrients (nitrates and phosphates) from the water.

The Algae filter needs minimal maintenance, every 3-4 days while it develops. And then every 7-10 days.

They are mainly used as filters for marine aquariums, and while some claim that it can be achieved by replacing the skimmer, others maintain it as a complement to the main filtration system.

Advantages and disadvantages of the types of algae filters

Advantages and disadvantages of algae filters

  • They help maintain a constant pH if lighting cycles in reverse.
  • It helps to lower the temperature of the water, since it produces a lot of evaporation.
  • They are very efficient at removing nutrients from the water.
  • They are cheap and simple.
  • They need more maintenance. The mesh should be cleaned weekly.
  • They take up extra space.
  • It is difficult to control the type of algae that develops.
  • The health of the algae must be kept under control, since if they die, elements are released that will unbalance the aquarium.

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