How To Maintain Fish Tank Filter

Fish Tank Filters differ in both design and type of filtration.

Filter designs

Internal filter

In the simplest case, they are a pump or an eirlift tube with a piece of foam sponge. The most difficult ones drive water through several layers of filter material.

The main advantage of such filters is the impossibility of leakage, as the filter is located inside the aquarium.

Air lift filter

The rising air bubbles (supplied from the compressor through the sprayer) pull the water upwards and create a flow of water inside the tube. The lower end of the tube enters the filter material, creating a water flow through it. Such filters are characterized by low productivity, therefore they are used mainly in small aquariums and spawning grounds.

How To Maintain Fish Tank Filter

External filter

External filters are a hermetically sealed container filled with filter material. Two tubes lead to the external filter: one comes in from the aquarium to the filter, and the other goes back. The return is due to the built-in pump, and the water supply to the filter is due to the difference in level (if the filter is below the water level in the aquarium) and due to the pressure difference.

The advantages of such filters include the following:

  • Do not occupy a place in the aquarium and they do not need to be masked – just put into the cabinet
  • You can detach and take it entirely to where it is more convenient to clean them.
  • Increase the useful volume of water
  • Improves the circulation of water, since the intake and return of water can be placed in opposite corners
  • The aquarist himself can choose the type, volume and combinations of filler
  • There are external filters of various designs, with different pump performance, for different volume of filler

Hinged filter

Such filters are mounted on the wall of the aquarium from the outside and are somewhere between the internal and external filters. It is used quite rarely, as it has most of the disadvantages, such as: small volume, possibility of leakage, low productivity, etc. But in some cases it may be the best solution when it is difficult to use both external and internal filters.

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Bottom filter

They use false-bottom: a cavity is created under the ground, from where water is taken with the help of a pump or air-lift, which then returns to the aquarium again. In this case, the soil in the aquarium acts as a filtering material. One of the advantages of bottom filters is the forced washing of the soil, which eliminates the formation of silty zones, but at the same time worsens the nutrition of plants through the roots. Also, it is not convenient to use and is not applicable in large aquariums. Now almost not used. It is included in the delivery of some aquariums, but most aquarists will be advised to first of all throw a false bottom and install a “normal” filter.

Filter functionality

Small internal and external filters use a foam sponge, which is also a mechanical filter and surface for settling a small amount of bacteria for biological filtration.

In almost all filters for aquariums, you can choose a set of fillers. The functions that the filter performs are almost entirely dependent on the types of these fillers. If there are several of them, the water must first pass through the coarsest, and then through more and more finely porous layers, otherwise the entire system will be clogged ahead of time. Most Fish Tank Filters are made universal and at the same time perform mechanical and biological filtration.

In large aquariums, several external canister filters are often installed. For example, one for mechanical and one for biological filtration. This facilitates their maintenance, since large cans are not so easy to maintain, and thus unnecessary maintenance of biological filters can be avoided. Sometimes several biological filters are installed when washing one can be dangerous for a loaded system. In addition, in long aquariums, a sufficient and uniform flow of water is difficult to achieve with a single filter, and this can cause the formation of stagnant zones.

Filter accessories


This is a plastic tube with holes. It is used to distribute the flow created by the water entering the aquarium and reduce its speed. It will help if the flow from the filter is too strong and it "blows away" the fish and plants.

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Lily pipe

Specially designed for vegetable aquariums tube return water, something like a funnel. Allows you to create a soft current, improves the mixing of water. The original version from ADA also includes a suction pipe designed for uniform water intake from different depths.

It is recommended to install the intake and return tubes in one corner of the aquarium to ensure circular circulation of water to improve the delivery of nutrients to plants throughout the volume.

When properly installed near the return bell, a turbulence is formed on the surface of the water, which prevents the surface of the bacteria from tightening.

Filtration in saltwater aquariums

In saltwater aquariums, traditional filtration is not used. A rare exception is the external “canister” filled with activated carbon. Mechanical filtering does not apply, since all waste products must be “recycled” or removed from the system as soon as possible. The nitrogen cycle in the “sea” is provided by live stones on which aerobic bacteria live. Mechanical and biological filtration can cause an effect, called a nitrate factory, in which nitrates begin to accumulate in the aquarium.

In fish “banks”, biological filtration is sometimes used, but in such a system it is necessary to take care of denitrification. In short: the export of nitrates is carried out:

  • Due to the special device – denitrificator.
  • Due to weeding of plants absorbing nitrates, for example hetamorphs.

Cleaning and maintenance of filters

Filtration of the filter occurs from time to time: a lot of detritus and other organic matter accumulates in the filter, which reduces the filter’s efficiency, reducing the volume of pumped water and the effective volume of the filter.

Materials for mechanical filtration, such as synthetic winterizer, foam sponges and others, should be washed, replaced as they wear out, or as a result of heavy contamination. If it is difficult to determine the need for replacement, you need to consult the filter instructions – they usually indicate the recommended frequency of replacement of filter materials.

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Silting biosubstrat leads to a decrease in its surface area, which also reduces the filtration efficiency. It is recommended to rinse the biological filter material only with aquarium water, as tap water can kill a colony of bacteria due to the temperature difference and additives contained in the water. Also, you should not leave biological filler out of the filter for a long time or in a disabled filter, since nitrifying bacteria that produce biological water purification require a flow of water that is rich in oxygen and nutrients for life.

From time to time it is necessary to update the biosubstrate, since the pores are gradually clogged and the effective area decreases. It is not necessary to replace the entire substrate at once, as this will mean an almost complete restart of the biological filtration system. It is better to replace the substrate in small parts once a month or several months. If a sufficient part of the old substrate with a colony of bacteria remains, then such replacements will pass without any harm to the filtration and the aquarium as a whole.

If during transportation of the filter it remains off for more than three or four hours, you can significantly prolong the life of aerobic bacteria, if you blow the biosubstrate with air using a spray gun and a battery-powered compressor. If, however, the biofilter remains turned off and without oxygen for more than 4 hours, it should be rinsed, because if the entire volume of dead bacteria spills out into the aquarium, it can poison the fish and other inhabitants.

Attention! Before you disassemble and assemble the filter, please read the instructions. Modern filters often contain fragile parts that are easily broken. Moreover, spare parts for filters are not cheap, so even if you cannot quickly find a replacement for the component you need, you will have to configure and run the filter again!