How to choose an aquarium filter

How to choose an aquarium filter

image source: Wikimedia Commons

Choosing an aquarium filter for your tank is a difficult task for beginners as there are different types of filters available in markets. A filtration system is responsible for keeping your aquarium clean and removing waste, and toxic elements present in tank water.

Once you set up a fish tank, you should need some basic ideas of types of filtration and filter type available before purchasing some filters which do not suit your needs. It is always advised to choose a filter based on the following requirements,

  • Size of your Aquarium tank(Big tank needs a more powerful filter as it has more water capacity)
  • How many fishes are you planning to put in the tank?
  • How often will you do the maintenance?

Types of filtration

There are mainly three types of filtration we can perform in an aquarium tank. You may get some basic idea about each in the following section.

Mechanical filtration

Mechanical filtration is used to remove solid particles present in water.

In this filtration, aquarium water is forced to pass through filter media like nylon, sponge, scrubbers etc. It will not remove chemical contaminants but helps to eliminate fish wastes.

Make sure you will remove the solid wastes in filter media regularly. Otherwise, fish wastes get converted to ammonia which is very toxic to fish species.

Chemical filtration

Chemical filtration is used to remove the organic pollutants formed by fish wastes from water, which cannot be removed by mechanical and biological filtration.

Chemical filtration use activated carbon which helps to eliminate chemical elements present in water which in turn helps to keep water and fishes clean and healthy.

Biological filtration

In biological filtration, toxic and waste elements found in water gets removed by the bacteria present in biofilters.

Fish wastes and food remains in water will form ammonia which is very toxic to fishes. Bacteria can convert ammonia into nitrites and then nitrates.

We can use filter media like bio balls, scrubber, metals, sponges etc. in the filter which helps in bacteria formation because of the surface area of the filter media. 

Aquarium filter types

Following are the types of filter available in markets. You can go through each type and choose a filter which suits your need.

Internal filters

As the name suggests, internal filters are placed inside aquarium tanks and these are fully submersible filters. Suction cups present in this aquarium filter helps to mount the filter to any side of fish tank. Filter sucks the water from the tank and passes water through the filter media where filtration happens.

A lot of internal filter models are available in shops. Most of the people use sponge filters in their aquarium.

In sponge filter water is forced to pull through the sponge media. Bacteria can quickly grow in the sponge which helps in biological and mechanical filtration.

Power Filter

The power filter is the most widely used filter by the majority of people. Power filter can be used to do all types of filtration.

Water passes through filter media helps in mechanical filtration which then goes through activated carbon, and then biological filtration happens in filter cartridges.

Canister Filter

Big tanks and tanks with more fish stock can use a canister filter for excellent filtration. It provides chemical, mechanical and biological filtration for large aquariums.

The canister filter is slightly more size compared to other filters. This filter is suitable for planted aquariums and saltwater aquariums.

Undergravel Filter

Undergravel filters are mainly mechanical and biological filters. It is kept below gravel layer as its name suggests.

Mechanical filtration happens when water passes through gravels and bacteria forms in between gravels help in biofiltration.

This filter is a bit low price compared to other filters.


Filtration technology has changed a lot in recent years, which helps the hobbyist to keep and maintain an aquarium without many efforts. 

Lots of aquarium filters are currently available in the market. Choosing an aquarium filter should be decided based on the size of tanks, stock of fishes and how much time you have to spare for maintenance activities. 

You can reduce your aquarium maintenance to some extent if you choose a good aquarium filter. 

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