Aquarium filter media types

Proper filtration of aquariums is an essential process in the hobby. We've discussed the aquarium filters previously, but the various types of filter media have not yet been elaborated. Which aquarium filter media do we use, and in what order do we load our filters here at Green Aqua? We like to share this with you. 

Mechanical filter media - the first layer in the filter cycle

One of the primary functions of a filter is to keep the water optically clean. We need to be able to filter out small floating particles. The mechanical filter media should always be the first layer of filtration. Sponges and fine filter pads are used for this purpose. The density of the sponges varies, and the number following the TM symbol in their name indicates this. The higher the number, the denser the sponge, and it's easier it gets clogged. Or another way, the denser the sponge structure, the more effective it will catch debris. In practice, translating this into sponges, we need to consider how much waste we expect over a period of time and select the density of the sponge accordingly. The TM 10 sponge is frequently called a coarse sponge, which can be used as an effective pre-filter surface as it traps most of the floating particles but does not need to be cleaned often. Then use a TM 20 or TM 30 sponge. By combining these, most of the physical particles can be filtered out effectively. They are easy to clean and can be reused in the long run. We replaced them when the sponge cells were no longer flexible and broke into pieces.

And what sponges can't catch, the fine filter mess (or cotton wool) will do for sure. This media can capture even the tiniest floating particles. However, unlike sponges, it is not worth bothering to clean them; as they disintegrate quickly, we recommend replacing them. It should be used as the last layer of filtration, making its replacement faster and simpler. Placing the fine filter mesh into the third layer of filtration (usually the chemical layer) forms an exception in our filter structure.

Mechanical filter materials also include ceramic rings and plastic pieces (manufacturers often add these components to their filter), which are also the first line of filtration. Their task is to catch and settle a large part of the residue. We don’t use these kinds of filter media. They are not as effective as sponges and biological filter material. Usually, we replace ceramic and plastic filter media with biological media.

Biomechanical filter media

Different filter materials are not necessarily capable of only a particular type of filtration. The sponges do not only perform mechanical filtration either, as there are helpful bacterial colonies in the gaps of the cells, which make the material biologically useful to a certain extent.

A good biomechanics filter media is the Eheim BioMech, which forms a transition between mechanical and biological filter materials with its coarse pores. Traditional lava stones can be used similarly for this purpose.

Biological filter media - the second layer in the filter cycle 

Sooner or later, the word nitrification comes to the attention of every aquarist. Indeed, this is one of the most important biological processes in the aquarium. Millions of bacteria that bring water to life are the soul and the foundation of every process in an aquarium and decompose Ammonia into Nitrates. These so-called "useful" bacteria are in large numbers in the filter. We also consciously place filter materials that provide excellent habitat for them with their porous surface. The bigger surface, the better.

A large number of filter mediums developed for this purpose are commercially available. We can sort them into two groups: the sintered glass types and rock-based media.

Going further, some could modify the water parameters. If your goal is to lower the pH, it is recommended to use ADA Bio Rio or Aquario Neo Media Soft, for example.

But sometimes, we look for stability. We do not want a significant change in water parameters. For example, in a soft-water planted aquarium, it is no longer necessary to lower the pH after CO2 injection. In this case, you may want to use Seachem Matrix, Aquario Neo Media Pure, or Eheim Substrat Pro.

Cleaning these mediums requires some care. We recommend rinsing the filter media in a bucket with aquarium water, as the bacteria is sensitive to tap water cleaning. This is also the proper way for mechanical filter media cleaning. This way, they can effectively continue decomposing the organic waste generated in the aquarium after the cleaning process. The process is called nitrification, which is so important in this hobby that it deserves a separate blog post later.

Chemical filter media - the third layer in the filter cycle

The fourth group of filtration, often used as an optional step, is chemical filtration. These filter materials help remove and neutralize medical products or filter out invisible floating particles. Purigen and activated carbon are the most popular ones, which can neutralize the undesirable coloring effect of any decoration wood (such as ironwood). We always try to use Seachem Purigen in all our filters, mainly to remove possible coloration of the water e.g., caused by wood. Activated carbon also removes chemicals (chlorine, drug residues, other chemicals). However, activated carbon use in a planted aquarium is only recommended for a shorter time because it can bind essential iron to aquatic plants.

Nitrate or phosphate binders are often used, among other products, to inhibit algae growth, but keep in mind that these can also inhibit the growth of aquatic plants.

In some cases, the water or sand/decoration's silicate content causes diatom algae growth. There is also a chemical binding resin for this. Most customers report spectacular improvements by using these to remove diatom algae.

Use only chemical filter mediums for a particular task. Specific chemical processes can also affect other things, which can change the balance of the aquarium. We use them only for a reason and with caution.

To complement this article and the topic of filters in general, we recommend watching our YT video "An Aquarium Filter Guide For Planted Tanks."

Do you need help with your filtration?

If you need help, please get in touch with our customer service, and we will be happy to help.