How To Make A Biofilter For The Aquarium With Your Own Hands

The need and meaning of biofiltration

In a number of types of cleaning – mechanical, chemical, biological – aquarium water biofiltration is, in the opinion of experts, the most important. What is the reason?

The fact is that in the aquarium there are always organic waste of fish and other animals, rotting organic matter. The decomposition of waste and gases exhaled by fish contribute to the release of ammonia, which, when dissolved in water, not only changes its properties, but also has a detrimental effect on the health of underwater inhabitants.

It is known from a school chemistry course that ammonia and some of its compounds (ammonium, for example) are toxic substances. As for aquarium fish, for them the lethal dose of ammonia is 0.2 mg / liter. For many fish, the maximum allowable dose is 0.02 mg / liter, but even with such a concentration, especially tender living creatures will not feel very comfortable.

Consequently, the concentration of ammonia and its compounds should ideally tend to zero. But how to achieve this? How to remove a toxic substance, if it is dissolved in a volume of water?

You can partially replace the water in the aquarium, and some aquarists believe this method is the best to reduce the concentration of toxins.

How To Make A Biofilter For The Aquarium With Your Own Hands

But daily substitution should not be done, since each such manipulation is not only a rather strong stress for aquarium fish, but also a certain disturbance of the formed balance of the home aquatic ecosystem.

And here come to the aid of beneficial bacteria, processing poisonous ammonia into nitrates, which are not toxic.

Thus, the biological method of water purification or biofiltration implies the mandatory participation of living microorganisms in the process of improving the quality of the aquatic environment.

Microorganisms themselves are present in the aquarium: on the walls of the jar, on the elements of decor, in the water. Of course, they neutralize part of the nitrogen compounds, but this part is very small. It is necessary to collect a large colony of these beneficial bacteria in one place and create a constant stream of aquarium water passing through this group.

The principle device of the aquarium biofilter has just been revealed in general terms.

Biofiltration in an aquarium is of great importance. And all because there is constantly waste of fish and other inhabitants, decomposing organic residues. Decomposition, as well as gases emitted by fish, contribute to the formation of ammonia, which, when dissolved, adversely affects the health of living beings. Ammonia and some compounds are poisonous.

So ammonia should be concentrated in minimal doses, and it is better to be completely absent. But how to remove a toxic substance if it dissolves in water? Replacing water in a pond with parts is the best way to reduce the amount of poison. However, this procedure should not be carried out daily, because it is stressful for the inhabitants and a kind of imbalance.

How To Make A Biofilter For The Aquarium With Your Own Hands

Here are useful bacteria that process ammonia into nitrates, which do not harm the inhabitants. Biological purification method requires the presence of microorganisms. Even without biofilter bacteria are present in the medium. They neutralize some of the ammonia compounds, but this is not enough. It takes a lot of good bacteria, so that they constantly get rid of toxic substances. The foregoing makes biofiltration necessary.

The principle of the biofilter

Special bacteria act as a biofilter. Their mission – to process ammonia into nitrates. Only with a filler, without useful microflora, filters for purifying aquarium water are useless. Mechanical elements can only hold up the dirt, but do not disinfect it.

There are 2 types of bacteria that are used for water purification:

  • nitrifying – are engaged in the oxidation of ammonia to hydroxylamine, which is processed into nitrite and nitrate;
  • nitrobacteria – they process nitrites into nitrates, which have a significantly less harmful effect on fish.

Beneficial bacteria are present by themselves in the aquarium, but in small quantities. They do not resemble a separate substance that can be collected and poured. The task of the owners is to provide a comfortable place for bacteria to breed. If there is adequate nutrition, then this happens quickly.

The ideal place for the maintenance of the vital activity of beneficial bacteria creates a biological filter for the aquarium. In the design of the device there is a special filler. It increases the contact surface with water, thanks to its porous structure. This gives a lot of space for beneficial microflora, which guarantees its active reproduction.

  • foam rubber or synthetic winterizer – the most common options that also allow to get rid of dirt;
  • bioceramics, gravel or pebbles – spray water, enriching it with air;
  • plastic fillers – also increase the oxygen content in the water;
  • cellular glass.

Biofilter device and types of filter materials

First of all, it should be noted that there are no devices that perform only biological cleaning of the aquarium aquatic environment. Every aqua filter (external or internal) provides at least two types of cleaning: mechanical and biological. Some devices also have chemical filter media. Thus, the biofilter is a component of the device, a very important part of it.

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Microorganisms that process ammonia should be able to settle on the substrate through which the aquarium water is pumped. There are several types of such substrate or fillers for biofilters, which are placed in special cassettes (compartments).

Foam filter. The most common materials are foam rubber and sintepon. They not only satisfactorily cope with the mechanical purification of aqua from solid impurities, but also are well suited for the formation of a colony of bacteria. These materials are used most often in internal filters with a small workload.

Their disadvantage is the rapid contamination and clogging of the pores of the material formed during the filtration of mucus.

Foam rubber should be washed frequently, and after that the process of formation of a colony of microorganisms begins anew.

Bioceramics filter. In external or, as they are also called, canister filters, ceramic rings or tubes (bioceramics) are often used as a filler for filter cassettes. They are not only an excellent substrate for the settlement of beneficial bacteria, but also a good spray of water carrying oxygen. And without oxygen, as is known, all living things die, including bacteria.

The filter from plastic elements. In many modern filtering devices, one can see such a filler as small plastic balls with a ribbed cut surface. Water passing through such a filter is sprayed, supplying more oxygen to working microorganisms.

Glass filter There is also a type of filter element, such as porous glass, which, thanks to a special manufacturing technology, is baked in a certain way. The result is a cellular structure, from which then small balls are made (with a diameter of 8 to 12 mm). Bacteria quickly colonize a similar substrate and successfully process toxic nitrates.

The modern industry produces a variety of biofilters with a variety of fillers of cubic, cylindrical, round shape, as well as combined options, such as, for example, plastic bio-balls with a sponge located inside.

For a start, it is worth mentioning that the filter, which purifies aquarium water only from a biological point of view, was not invented. Any filter holds at least two cleanings: biological and mechanical.

Bacteria should be placed on the substrate water. There are several types of such a substrate or filler for a filter that fits into designated areas:

  • Foam filter. Popular materials for the filter – foam rubber and sintepon. They cope with the purification of harmful impurities, as well as create an army of microorganisms. More often such materials are used in internal filters at low load. Their only disadvantage is the rapid accumulation of dirt and blockage, which occurs as a result of the mucus that appears during filtration. Foam rubber needs to be constantly washed, after which the army of bacteria begins to form in a new way.
  • Bioceramics filter. In external filters, rings or ceramic tubes often act as fillers. It is an excellent substrate for the formation of beneficial microorganisms, and they also do a good job of spraying water with oxygen. And without oxygen, life is impossible, including for bacteria.
  • Plastic filter. In most of the existing filters in the role of filler, small balls of plastic. Water passing through a similar filter is sprayed, which gives a large amount of oxygen to bacteria.
  • Glass filter. There is also the option of a filter made of porous glass, which is baked in a special way using a special method of manufacturing. The result is a material with many cells, from which small balls are made. Microorganisms spread rapidly and neutralize toxic substances.

In the modern world there is a huge number of filters with different types of fillers of various forms, as well as combined options, for example, bio-balls made of plastic with an internal sponge.

Video about the choice of biofilters for the aquarium.

Device description

The volume of the aquarium affects the design of the bio-cleaning system. The greater the capacity, the more difficult the filtering device will be. Large systems contain additional compartments for multi-stage cleaning. As well as manufacturers equip such models with means to control the water supply and the quality of its filtration.

How To Make A Biofilter For The Aquarium With Your Own Hands

Components of a simple biofilter:

  • tube – sprays water;
  • compressor – supplies air to the nebulizer;
  • filter element.

Homemade Aquarium Biofilter

Tetra EX Filter

The German company Tetra has long established itself as a manufacturer of reliable aquarium equipment, including filters. Devices of the middle class Tetra EX provide a decent level of cleaning in aquariums with a capacity of from 60 to 500 liters.

As a filler for biofiltration, both ceramic rings and bio-balls are used (depending on the model).

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Devices of this brand belong to the lower supply systems, and the water is cleaned when it comes under pressure from the bottom up, passing through cassette-type fillers.

A feature of the technical device is that before turning on the filter in the network, it is necessary to create a manual thrust and fill the canister with water. To do this, in the upper part of the body there is a swap button.

JBL (Germany) specializes in the production of energy-saving filters. Biological cleaning in models of the JBL line is made in bioceramic fillers. Water enters the device from above, goes down along the side walls, passing the prefilter (mechanical cleaning), and then rises upward through the biosubstrate under pressure. Preparation of the system for operation is carried out in the same way as in the previous case.


Polish canister filters brand Aquael are very popular due to the low price and reliability. Filtration quality is average.

Instruments line Aquael able to clean the water in aquariums with a capacity of 100 to 700 liters.

Thus, the Unimax system, designed for large quantities of water, has two retractors and exhaust pipes. This results in improved mixing of the aqueous medium.

A colony of beneficial microorganisms located in a filler (bio-balls or ceramic rings) receives more dissolved oxygen.


It is impossible not to dwell on the Italian devices. Reliable and reliable systems from Ferplast have proven themselves in the work. Water enters the canister from top to bottom and, after mechanical cleaning under pressure, flows upward, passing through cartridges with filler (special sponges are used for bioceramics and varying degrees of porosity). Devices can work for years without leakage. The main thing is to maintain the filters in a timely manner without disrupting the technology of their disassembly and assembly.

Hello dear aquarists!

Today you will learn how to make a homemade aquarium biofilter. I guarantee a lot of impressions and pleasure from his work. So let’s go!

What is a biofilter and for he need? Let’s start with the fact that in the water, as in the air, a lot of rubbish rotates: micro algae, food particles, scales and other suspensions that fall from the outside and pollute the water. Do you need dirt and mud in the aquarium? Right, not needed. That’s it for this and there are various Fish Tank Filters.

For those who believe in themselves and their strength, I recommend making a simple but effective homemade aquarium biofilter. That’s how smoothly we approached the process of making the filter.

To manufacture an aquarium biofilter, we need: a soldering iron, a plastic floor liter bottle of juice or water, a piece of galvanized or plastic tube (the tube diameter must be such that it fits tightly into the neck of a plastic bottle), 7-8 tablespoons of fine gravel or pebbles , a little padding, dropper and aerator (I mean compressor). Now for the job.

Take a plastic bottle and make a glass out of it: cut the top of the bottle. You will have a separate plastic “glass” and a small plastic “glass” separately. We heat the soldering iron and take our “little glass” in our hands.

In this glass you need to melt the holes around the entire circumference. Best of all, if you melt two rows of parallel holes. Just poke a soldering iron quickly, otherwise the “glass” is deformed.

We assume that you have coped with the task. What’s next?

And then we take a segment of the tube and insert it into the “glass”, but not from the outside, but from the inside.

But again: do not overdo it, because the tube should fit in very tightly, and not loosely! When the tube passes into the neck, simply stretch it almost to the very end of the "glass": you should have the following construction – a plastic "glass" worn on a piece of tube (the tube should be just below the upper cut of the "glass").

Further. we take the resulting construction (“glass” on a stick), insert it into your plastic cup (which remains from the bottle) and push the “glass” on a stick to the bottom of the glass.

Now we take the soil – pebbles or gravel – and begin to evenly pour it into the glass (not into the tube!). The soil falls to the bottom, covering the "glass". The height of the soil in the glass should be approximately 6-7 centimeters.

Fill the remaining free height evenly with padding polyester.

In conclusion, I want to point out one important detail in the work of the aquarium biofilter. In the process of its work, colonies of beneficial bacteria develop in it, which neutralize harmful substances in water and soil.

So, if you turn off the biofilter for several hours in a row, then this whole colony will die, and this is very bad. Therefore, if you want to let the compressor rest, turn it off for no more than an hour.

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All the best to you and to new meetings!

DIY creation

Simple option

A small aquarium holds a small amount of water. To clean it will need less bacteria. Consequently, the body of the biofilter can also be made small.

How To Make A Biofilter For The Aquarium With Your Own Hands

Components and tools:

  • plastic bottle;
  • nail, you can use the awl;
  • foam rubber;
  • filtering filler;
  • gum round shape;
  • spray.

Complex components are missing, so you can proceed to installation immediately. It is unlikely that something will be absent in the household.


The range of models of biofilters is very wide. But choosing a particular device, you must first take into account its performance.

Experts believe that the minimum performance of this device should be at least two full volumes of water per hour, and better – 3-4 volumes.

This is the only way to stop the accumulation of toxins dangerous for fish in the aquatic environment. For example, if there is an aquarium with a capacity of 120 liters, then you can choose Aquael MiniKani 120 aqua-filter with a pumping capacity of 350 l / h.

Thus, in order to preserve the life and health of your pets, you should know the causes of the appearance in the tank of poisonous substances and ways to combat this phenomenon. This knowledge will certainly help when choosing the desired biofilter.

Biofiltration home aquarium

For many amateur aquarists, the problem of biological water purification is of paramount importance due to the fact that they want to have representatives of those species of fish that are very demanding on the quality of water.

These are the discus, cichlids, and those for which the natural habitat are fast-flowing reservoirs.

Biofiltration is also important for fish of large species, because their waste products pollute the water in the aquarium quickly and severely.

In nature, water in rivers, lakes and seas is cleaned with natural filters. They do an excellent job with this in the absence of the negative influence of human activity (discharge of waste into water).

In the artificial domestic pond, to which the aquariums belong, the mechanisms of natural water purification also operate, however, due to the limited volumes of aquariums, they do not give any significant result. For this reason, a closed aquarium aquatic system requires external intervention to create its fauna and flora in a comfortable habitat.

Biological water filtration is one of the options for such an intervention. For such types of water purification in an aquarium, such as mechanical, chemical, biological, biological filtration plays a special role.

Advantages of biofilter

The presence of a biofilter makes it easier to take care of an aquarium and takes much less time to maintain than an aquarium with traditional filters. Those who think otherwise are held captive by stereotypes.

When using a biofilter, the aquarist does not need to worry about removing organic matter that is not naturally degradable from the reservoir (fish excreta, decaying plant leaves, food residues, etc.). He should focus on the current maintenance of the inhabitants of his aquarium:

  • feeding fish
  • regular water changes
  • periodic washing of mechanical filters.

The biological filter does not have any fundamental influence on the regular processes occurring in the aquarium after it has established bio-equilibrium. The biological filter only contributes to the stabilization of this equilibrium and makes the flow of regular processes in the aquarium more intense.

How To Make A Biofilter For The Aquarium With Your Own Hands

Keep in mind that manufacturers of aquarium equipment produce aqua filters that carry out at the same time different types of water treatment (mechanical, chemical), and not just biological. The biofilter in this equipment is its component along with other types of filters.

The device of the biofilter is such that the beneficial bacteria that can neutralize harmful nitrogenous compounds, are able to settle and multiply on the substrate, through which there is a constant flow of water. Manufacturers use different fillers in their filters. They fit into special compartments and are thus fixed in a certain position and are not moved by a water jet.

The lineup of biofilters is long and you need to properly navigate. The main criterion for each aquarist that he should follow when purchasing this equipment is performance.

Most professionals agree in one opinion: the optimal performance of an aqua-filter is the omission of two full volumes of water in an aquarium per hour, the ideal is to clean three to four volumes of water per hour. It is this bandwidth biofilter neutralizes toxins and heals the habitat of aquarium fish.

For clarity, we give an example. If the volume of a home aquarium is 120 l, buy a filter with a capacity of 350 l / h.