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Filtration and Filtration Methods:

Filtration, as you know, is an essential part to maintaining any aquarium. This is especially true with discus aquariums. If you didn’t use some sort of filtration, the discus would soon succumb to health issues, and if left alone, would eventually die from the toxins which build up in the water. This section will explain more about various filtration methods and guide you in properly maintaining a balance in your discus aquarium. We will be covering the following; The Nitrogen Cycle, Mechanical, Biological, Chemical, Activated Carbon, Resins, Fine Filters, Filter Flow Rate, Peat and Blackwater Extract.

The Nitrogen Cycle:

Before we can start to talk about other filtration methods for keeping your discus aquarium clean, we first must tell you about the natural filtration already happening in the water.

Beneficial bacteria, also known as bacteria, make their home all over the tank. These nitrobacteria consume the toxic ammonia which your discus fish generate when they defecate. The ammonia that these nitrobacteria consume is broken down into nitrite. What happens next is a second nitrobacteria consumes the nitrite created by the first nitrobacteria, and further breaks it down into nitrate. This whole process is known as the nitrogen cycle, and is the main pillar biological filtration.

Nitrate is removed from the water by performing water exchanges every now and then, or by utilizing specific resins. This section will go over those specific resins in detail later on.


The first method of filtration on the list is mechanical filtration. The main objective of mechanical filtration is to get rid of any floating particles on the surface of the water in your discus aquarium. These particles are usually comprised of uneaten food, fish waste, or plant parts. There are many things you can use for this task such as; sponges, pads, floss or a commercially purchased skimmer.


Depending on what your filter set up is like, you usually use these sponges in the area where the water enters into the filter, generally called the intake tube. Some filters have these sponges located in special areas.

There is even a rather simplistic filter set up that involves only an intake and outtake and the sponge in a tube. This is called a sponge filter, and if used properly can run a discus aquarium for quite a long time.

It works by taking in the particles and catching them in the sponge. You need to clean this filter at least once a week by squeezing the sponge out in a bucket of the same water as what is in your discus tank.

The left over nitrobacteria will take care of the nitrites and turn them into nitrates perfectly using this system, making it a perfect companion to a biological filter. While it could be used to completely replace a biological filter, it is always a good idea to have one in your discus tank as well.


Pads function much like the sponges do, in that you generally have them set up somewhere around the intake tube for the filter. As mentioned before, some filters have special compartments where the water enters, and this floss catches all the floating particles which could potentially clog up your filter.


This floss looks like something akin to the kind you use to pull the extra bit of food out from between your teeth. It is crisscrossed in a sort of net like pattern. You generally find floss in the box-type filters that use a combination of gravel as well as the floss. It works by catching the particles and preventing them from entering the filter.

Commercially Purchased Skimmer:

Of course you can just opt to use a commercially purchased skimmer, rather than bother with using any of the aforementioned methods with your filter. While it does save the trouble of having to clean out the filter, you will be required to skim the surface of the water every few hours, and even then some of the particles may make their way into the filter and clog it up.

What is very important to remember is that although the filter is doing its job of catching all these particles and keeping the water clean, you must clean out the filter manually at least once a week. In some cases, depending on the number of discus fish you have in your tank, the number of plants you have, and how big a tank it is, you may need to clean out the filter two or more times a week. However, if you are cleaning out the filter that often, you may want to consider getting a different filtration system, getting rid of some discus, or even moving them to a bigger tank.