Best aquarium - planted tank
Best aquarium - planted tank

Best aquarium filters and filtration

One of the most important inventions that allowed us to keep fish in tanks was the best aquarium filters.  As a fish goes about his (or her) day they produce waste material. This can be actual excrement or uneaten food or other fish which have died. The filter has the role of cleaning the aquarium water of impurities and oxygenating the water. No tank should be deprived of this device because it has an important role in maintaining a clan and healthy water for the fish. In stores you can find several types of filters, depending on the position or method if construction.

Why you need an aquarium filter for your fish?

In the sea this would be broken down by the bacteria in the water. The bacteria would turn it into other chemicals. These chemicals would be consumed by plants and the water is clean again. Since the sea is so big there is plenty of time for this to happen without any health risk to the fish.

In your aquarium this filtration process needs to be fast. Waste products have to be removed constantly and efficiently because there is a higher density of fish in the water and you don’t have the luxury of other plants and animals to deal with the waste. This is where the aquarium filter comes in.

The filter will have water pass through it and collect debris. This removes the harmful chemicals from the water and the fish live a happy and prosperous life.

There are three types of filtration


Biological Filtration

This is the process by which the water is sucked into a aquarium filter and passed through a sponge or other fish tank filter materials which have been allowed time to have bacteria form on its surface.

As briefly mentioned above, in the sea bacteria would breakdown the waste of the fish. This process if now done in the aquarium filter, with higher levels of bacteria for the quantity of water.

This is the most common type of aquarium filter and the only one that a tank must have to be filtered effectively.

Mechanical Filtration

This is when any solid matter is removed from the tank. This can be done by hand with a net. This is also often done with a siphon which is used to change water for fish tank.


A mechanical filter is also available as part of an aquarium filter.  The aquarium filter will have a powerful suction which will slowly gather debris from the tank and this will be caught in the filter and eventually broken down before being passed through the biological filter.

This whole process is flawed in a sense. Any suction powerful enough to attract large debris will be powerful enough to affect the fish.

Also the larger waste would take too long to filter fully and would need to be removed from the system rather than just filtered.

There are mechanical filters which catch any large pieces of waste in a sill or trap which you can empty manually and this is a much more effective method and should be chosen over the flawed method above.

Chemical Filtration

This is the process that plants perform in the sea. They take the dissolved chemicals which are in the water and use them to grow.

Due to the increased density of the aquarium compared to the sea you would not be able to have enough plants to the amount of fish you would keep in the aquarium.

Luckily to help with this they have a chemical filter which uses materials such as activated carbon to breakdown and store the chemicals which were in the water. This is the least common type of aquarium filter.

If you are looking for an aquarium filter for a small to medium tank which is not over populated then you will probably only need a biological filter.

If you have a large tank or you have a complex community of fish you will need to tailor your aquarium filter to your needs.

Different aquarium filter types

Internal filters, are mostly used by beginners, they are inserted completely in the tank. They consist of a pump that pulls water through a sponge, so that impurities remain trapped in the sponge mass, resulting in cleaner water. There not the most efficient filters because the sponge is quit small and the water doesn’t get cleaned very well. But have the advantages of being very cheap (price starting from 5$) and east to install and use. One of the most popular brands on the market is: Resun, Aquael, Fluval etc. The options are many, you can choose according to you budget and needs.


External filters, are positioned outside the aquarium, have higher filtering surface, they are also more powerful and more efficient in every way over the internal filters. There only disadvantage is the price, they are the most expensive from all the filters, with an average starting price of 100$. They are indicated for larger aquariums, like 40 gallons or more, but these kinds of filters are available for smaller tank too.


  • External filters are more efficient at removing debris due to the higher quality of filtration media available as well as better built systems.
  • External aquarium filters are easier to replace the media in than internal filters.
  • Often external filters simply have a cradle for the medial which can be lifted out of the canister, you then replace the media and put the cradle back in the canister and you are done.

The internal filter does have the benefit of being cheaper (especially if it came free with the aquarium) and there is less risk of things like leaking or mechanical failure.

Although it may come down to preference or cost for someone looking to have a small home aquarium. The external filter is the better option should you be able to budget for the additional cost.