Aquarium Filter Media Type and The Arrangement

Every fish tank needs a filtration medium to clean the water. And each of the filters may it be a simple sponge filter or a Hang on the back filter or a canister filter or an advance filter sump filter, needs filter media in it. The purpose of a filter in the fish tank is to eliminate fish waste, excess food, floating dirt particles from the tank water. Filtration is necessary for every type of aquarium because it keeps the water clear and also keeps the inhabitants healthy and safe. One of the most common topics that come up repeatedly is the types of aquarium filter media and the order of placing media.

There are primarily three types of aquarium filter media that is used to carry out filtration in an aquarium. This includes Biological Media, Mechanical Media, and Chemical Media, each serving a different but vital purpose.

The Three Aquarium Filter Media Type:

Biological Media:

Aquarium Filter Media Type

One of the best types of filtration media is Biomedia or Biological Media. Biological media is placed after the mechanical filter media and before chemical media. This is because bio-media houses beneficial bacteria or nitrifying bacteria that help breaking down dissolved solid waste into a less toxic form. Therefore the media must not be clogged.

The media provide a physical surface for the bacteria to grow on. If your bio-media is clogged, the flow of oxygen will be impeded risking the beneficial bacteria to die.

In addition, all of the fish tanks require at least one of the type of biological media to house beneficial bacteria in it and most of the filter nowadays comes with biological media in it.

The bacteria can grow on any surface, but don’t simply spread out throughout the tank. Nitrifying bacteria tend to grow on the surface where there are most food and oxygen, which means where there is the most flow i.e. in the filter.

In general, you should never need to replace your media. But, you must clean biological media minimally, just enough to remove all the visible debris. The older your media is the better it will filter your tank water.

Learn the biological filtration more detail on our article: The Aquarium Nitrogen Cycle.

Some of the types of biological media are:

  • K1, k2 medias
  • Bio-ball
  • Fluidized bed
  • Foam
  • Ceramic rings

Mechanical Media:

Aquarium Filter Media Type

When you are using the sump filter or the canister filter, the mechanical filter is the first media that you will be placed in your filter. Mechanical Media the other aquarium filter media type that is the simplest one. But, one of the most common ones among other filter media. It involves passing tank water through mechanical filters (any type of filter) that acts as a strainer to catch dirt particles that are present in the water. Thus, this filter media removes large particles for the water preventing these particles to clog the biological media. There are various types of mechanical media. Finer the quality of media, the more waste particle it can trap.

The mechanical media simply makes your work a little easier. It helps you to collect debris and particulate waste and your job as an aquarist is to remove it from the system. If you don’t remove the waste then it will simply rot, degrading your water quality and risk your fish life.

Some of the types of mechanical media are:

  • Sponge
  • Filter Pad
  • Gravel
  • Filter Floss
  • Foam block


Chemical Media:

Aquarium Filter Media Type

Chemical Media is the other aquarium filter media type that is used in extreme cases or at the beginning of fish keeping when you need to boost up the nitrogen cycle in your tank. We use chemical filter media to remove toxins and poisons out of the fish tank. Hence, your tank water becomes healthier for your fish. The most common chemical media is using activated carbon, usually included in all filters. Carbon is very effective at removing toxins, odds, discoloration from the tank water. Since the carbon absorbs or removes the chemical from the tanks water, it should not be used when your fish is sick because it absorbs medicine too.

The reason behind the chemical filter to be placed after the biological filter is due to the reason that the media removes any odds or toxins. As the bacteria in the bio-media feed on toxins like ammonia and nitrite, placing the chemical media before bio-media prevents the food from reaching the beneficial bacteria. As a result, bacterial colonies will be less likely to thrive in bio-media.

Some of the types of chemical media are:

  • Activated carbon
  • Granular Ferric Oxide (GFO)
  • Poly-Filter
  • Crushed coral
  • Seachem Purigen
  • Ammonia chips

Media Order:

types of aquarium filter media | Media Order

Water in the filter should go through the following order may it be a canister filter or a sump filter:-  Coarse Mechanical Media, File Mechanical Media, Biological Media, and Chemical Media. In an aquarium filtration system, all of the three aquarium filter media is recommended. But, a fish tank at least requires mechanical media and biological media. Furthermore, the media in a filter must be arranged in the order as shown in the picture. By placing fine Mechanical media before biological media you prevent those media from being clogged by the fine particulate waste, as a result, you get a great filtration in your aquarium.

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