Aquarium Filter: Guide to the right filter technology

Every aquarist knows that Aquarium filters. Be it in the design of the internal filter, or also in the design of the external filter. There are also many special filter systems such as additional filter tanks, mat filters and large filters for breeding systems. In this guide, we want to shed some light and explain the advantages and disadvantages of the respective filter systems to you. We not only examine the function, but also the price, durability and care. Aquarium filters are available in a variety of designs, sizes and prices. 

 

Why does an aquarium need a filter?

Let's start with a question of understanding why we need a filter in the aquarium at all. Wouldn't it be enough just to circulate the water with a pump? After all, the fish only need oxygen to live and this is also ensured by good water movement on the surface. So isn't that enough?

Clearly no. That is not enough. The filtering ensures that the biological cycle in a microcosm like the aquarium remains intact. But let's start with the basics of everything that belongs to this cycle.

Plants need nutrients and light to grow. Therefore, aquarium lighting is extremely important. See our Guide to Lighting. If the plants grow well, pollutants in the aquarium water are broken down and oxygen is produced at the same time. This in turn is necessary for the fish.

However, fish also excrete certain things. This includes not only the Kod, but also the leftover food residues. Plants also produce waste in the aquarium. Mostly from dead leaves. Filtering is required to ensure that this waste and pollutants do not pollute the water.

These deposits produce nitrite in the aquarium, which is extremely toxic. See also our guide to aquarium chemistry. Nitrite can kill fish when present in high concentrations. Nitrite is in turn converted to nitrate, which is then again harmless to the fish. Fish can handle nitrate well. Bacteria are needed for nitrite to become nitrate. These are called Nitrobacter or also called Nitrosomona. The latter bacteria are responsible for converting ammonia into nitrite. Microorganisms are needed for these bacteria to develop. These usually occur in the filter mats. An important reason why an aquarium filter is needed.

Anyone who can still remember why you shouldn't immediately add fish to a new aquarium "keyword aquarium first running in" will quickly see the connection. At the beginning there are no nitrobacter and therefore no conversion of nitrite to nitrate. That's why a filter is so important.

A filter therefore has several tasks which it has to master:

 

• Provide surface agitation to produce enough oxygen
• Oxygen production or oxygen enrichment
• Flow generation for special types of fish
• Mechanical and biological filtration of the aquarium water

 

As you can already see here, a lot depends on what a filter has to bring with it. In addition to the size and performance, there are other points such as the selection of the filter medium and the placement in the aquarium.

 

Aquarium Filter: Mechanical filtration

Let's start with mechanical filtering. Basically, what is meant here is filtration, which simply pulls the water over a filter medium such as filter floss or filter mats. In new aquariums, i.e. without bacterial strains, there is only mechanical filtration because nothing else happens on the filter media.

Mechanical filtration is used to filter large particles and, depending on the filter medium, also very fine particles from the water. Water with a certain level of turbidity, especially when it is newly installed or redesigned, quickly becomes cloudy. Mechanical filtration quickly removes these particles.

 

 

Aquarium Filter: Biological Filtering

The aquarium is already running in with the biological filtering. Before that, one cannot speak of biological filtering. Strains of bacteria such as Nitrobacter or Nitrosomonas have emerged and are now breaking down cod and other waste in the aquarium.

Above all, the aquarium filter must be able to break down the toxic nitrogen compounds. For this 

he needs a wide variety of filter media. Be it filter sponge, which must be bacteria-resistant, or filter floss for fine filtering. Above all, however, the filter floss of the mechanical filtering and removes particles in the aquarium water. But more on that in the chapter on filter media.

 

 

Difference between chemical filtration and biological filtration

Again and again one reads about chemical filtering in various literature. Here the water is treated with appropriate chemicals and thus filtered. We would not call this type filtration as they are most often added as additives to a mechanical or biological filter. Certain preparations are often placed on an existing filter medium in order to influence certain values ​​such as the carbonate hardness or the overall hardness of the water. The PH value can also be influenced with the help of chemical additives. Again and again one hears about the peat filtering. But more on that later.

 

What are absorbers?

One reads again and again about absorbers. Especially with the many manufacturers of filter systems and filters. Absorber is basically nothing more than a sponge. They absorb certain substances and remove them from the water. These are used, for example, against nitrate or phosphate. You have to be careful with these mostly granulate-like filter media that they are replaced or removed in good time. If this does not happen, they quickly release the captured substances.

What filter media are there and what are they for?

Not every filter medium is suitable for the degradation of certain substances and not all filter media can be used in corresponding aquariums. Here, too, we only go into the filter media in fresh water. If you have a saltwater pool, you will need additional facilities.

 

 

But let's start with the question of what kind of medium should go in my filter.

Filter mats polyurethane

The filter mats are certainly the most widespread. These are available in different sizes and also in different pore sizes. Depending on the case, they are only used for mechanical or also for biological filtration. The unit of measure for pore size is called pores per inch and is given in PPI by the manufacturers. The smaller the number, the fewer pores are found in an inch. So the filter is coarser. The larger the number, the finer the filter becomes.

 

 

When choosing the filter mat for the aquarium filter, you have to choose the pore size according to the fish or shrimp. Crucial mistakes are often made here. Shrimp can quickly get behind the filter mats and die there.

 

We ourselves have always bought these filter mats in large sizes and then cut them to the required size. This can be done quite easily. Usually you get a better price from the manufacturer.

Filter mats are mostly used in mat filters and breeding systems. But more on that later.

 

Filter floss polyfibre

The filter floss is not only cheap, but also quick to replace. As the name suggests, you will find very fine pores here and therefore it is used in mechanical filtration to filter fine pores and suspended matter out of the water.

A biological filtering takes place rather less, as with the filter mats. However, it has a very long history. At the beginning of aquaristics, mostly only filter cotton was used for filtering. Cleaning and replacement is very easy.

 

Glass ceramic tubes / tubes

The glass ceramic tubes / tubes can also be found in specialist shops in various sizes. This is mostly about the first layer in the filter and the coarse filtering. Due to the special arrangement of the tubes, it is also possible to enrich bacterial strains inside. Probably the greatest advantage of this filter medium is the extremely long service life and the fact that it can be washed out. Quickly cleaned under appropriate water and it can be placed back in the filter.

 

Plastic filter media for the first layer

Coarse filter media find their place in the first layer (usually with the external filters). These are often natural products, but plastic media can also be used. Here the manufacturers offer a large selection. Be it various plastic filter cubes or filter balls and filter balls. In addition to the purely mechanical filtering, bacteria also settle here, so that the biological filter can also be reached after a while. We are not particularly impressed by these plastic balls and would recommend other filter media.

Absorber Phos Ex, SilikatEx, Phosphate out or NitratEx

As already described above, there are also so-called absorbers. As the name suggests, they absorb certain substances from the aquarium water. Well-known manufacturers such as JBL but also Tetra and Co have various products in their portfolio. Of course, we are entering the area of ​​chemical filtration here. The use of these media should be carefully considered. You can often achieve the same goal with the help of natural resources. Be it to reduce the silicate in the water or to lower the phosphate as well as the nitrate value.

 

Clay tubes, mechanical hollow body material, granules, volcanic filter material and bio filter material

The manufacturers, be it Eheim, but also Fluval and Juwel, are always coming up with new products in the field of filter material. Be it volcanic filter material, certain hollow bodies mostly made of ceramics, but also made of clay, various granules with different grain sizes or special organic filter material.

The purpose is always the same. One tries to create quite a lot of surface area through this biological filtering in order to give the bacterial strains a good basis and food. In addition, particles and suspended matter should also be filtered out of the water.

 

Activated carbon filter medium - filter carbon

This medium is also used again and again, although most people only use this absorber sporadically and not permanently. The activated carbon filter medium has a very good function - filter carbon, especially when it comes to cleaning the water from these substances after treatment with medication. It is very well suited for this, whereby the exact manufacturer's instructions must also be observed here. You have to take the coal out again at the right time. Otherwise the absorber function is done quickly.

Cleaning agents can also be bound with it, should it ever happen that washing-up liquid or cleaning agent (soap) gets into the basin. Then you should quickly resort to this filtering with carbon.  

peat filtering

Let's come to another filter medium for the aquarium filter, which is mainly used if you want to lower the PH value of the tank. Of course, the PH value can also be lowered with other things such as Co2 fertilization or changing the water. However, filtering over peat of any kind offers some advantages. Peat not only lowers the PH value, but also the carbonate hardness and has an antibacterial effect. Peat is also said to have an anti-fungal and anti-algae effect. Peat is very often used in breeding tanks in particular. Protection against spawning fungus is the priority here. Plant growth and the rich colors of the fish can also be influenced by peat. The latter especially when fish from peat-rich waters are used.

Should you have before over to filter peat, then you don't necessarily have to buy it in a specialist shop, but can also use peat from garden supplies. Here you just have to make sure that it is not pre-fertilized. This is mostly the case.

We will be publishing another guide to peat filtering shortly.

Don't be surprised if you filter through peat that the water gets a certain brownish color. This certainly doesn't look great, but it does have its perks.

The parts of an aquarium filter

Basically you have to distinguish which filter you are using. However, most filters have similar components. These usually consist of hoses or pipes, depending on the size of the filter. From the filter media and from a pump, which ensures circulation. Of course, these are available in different designs, sizes and outputs. Whether pond pumps, centrifugal pumps or air pumps. to compressors.

 

What types of filters are there?

First you have to distinguish whether it is an external filter or an internal filter. Below we explain the individual types.

Internal filter

Probably the simplest and usually the smallest available filter is the internal filter. It is hung directly in the aquarium, as its name suggests. It has an area where the water is sucked in and then passed over a filter medium. At the top, the water is directed outwards again and thus ensures a movement of the surface to enrich it with oxygen. The internal filter is usually quite small, but can also be used for larger tanks. The filter medium is quite flexible, although only a little filter material can be used here due to the rather small designs. One usually relies on filter mats. The type of filtering here is biological.

In specialist shops you will find a large selection of internal filter designs. Be it with a combination of flow pump or with an integrated heater. A diffuser to enrich the water with even more oxygen is often installed.

Cleaning is quite quick, but has to be carried out very often, especially in small pools and small filters. Be careful when handling electricity, because the 230 volt pump is located directly in the water.  

 

 

Internal filter air operated via foam - foam mat filter

Another internal filter is the internal filter which is only operated with air and therefore the air pump does not have to be in the aquarium but can be placed outside the tank. This brings a number of advantages. Most of the time, these foam mats are quite cheap, but have little filter performance.

Here, with the help of a pipe and the negative pressure, water is sucked through a small foam ball and this creates biological filtration.

Basically, you understand the principle of the air lifter with this filter. The negative pressure ensures that the water is lifted with the help of the air. Basically a modification of Hamburger mat filter, which we will introduce next.

 

 

Hamburger mat filter with air lift HMF

This filter is also an internal filter, since the filter medium sits directly in the basin. This type of filtering is mostly used in larger systems with many pools. We ourselves have used this in our breeding facilities and can only report positive things. Above all, the possibility of the large filter material must be mentioned here. At the Hamburg mat filter plastic filter mats of all sizes are used. These can either separate an entire area of ​​the aquarium or just a smaller area across the corner. You can even equip the entire floor with a Hamburger mat filter.

There is a tube between the filter mat and the glass of the aquarium, which is routed through the filter mat or over the filter mat. An air hose from an external air pump is used at the bottom end of the tube. This also uses the air lift principle to ensure that water is transported from the bottom to the top. Due to the negative pressure, water from the other side of the aquarium has to go through the filter. Bacterial strains therefore also accumulate here.

Hamburger mat filters are quite easy to make yourself. With large collecting pipes, several pools can be supplied with air at the same time.

Another good thing about this species is the extremely long running time. Running times / downtimes of many months are very often possible here, which is virtually impossible with an internal filter.

Instructions for the Hamburg mat filter and instructions for the air lifter in the video

 

soil filtration

This option is also available, but we would advise against this method. The functional principle and the setup is quite simple. Under the actual aquarium floor, a filter mat and underneath a pipework is placed, which drains the water upwards. With the help of a pump, the entire floor is used for filtering. The disadvantage is quickly obvious. Although it is quite easy to build the filter yourself, just think of the cleaning and eventual transformation with plants. Cleaning is not possible without completely replacing the soil and care must also be taken when replanting. This is why these undergravel filters are no longer widespread today.

 

backpack filter

The backpack filter is a middle ground between external and internal filters. It is simply hung on the back of the aquarium pane and has the filter medium in its backpack. The water is then fed from the pool through the filter media and back into the pool. This filter makes sense for smaller tanks. It is less likely to be found in larger aquariums.

 

External filters from 50 liters to several hundred liters

You will not use an external filter with less than 50 liters today, since the power density would be too high here. Anything above that makes sense for an external filter. The conventional external filter is constructed as follows. He usually sits at the bottom of the aquarium cabinet. Inside, there is room for the filter media in different layers, mostly from coarse to fine. Above or at the upper end of the filter is the pump, which takes the water at the bottom of the aquarium through hoses and delivers it back to the surface of the aquarium through a second hose. Thus, the water is circulated over the filter media.

The advantage here is the long service life and also the possibility of a large filter surface and individual equipment. Nothing has to be put into the pool when cleaning. Unfortunately, there are also disadvantages. The main thing to mention here is the piping. If there is a leak here, the aquarium water will run out. Nevertheless, this species is the most widespread today. It is of course also possible to combine several of these external filters.

 

 

 

Filter basin, trickle filter or other special shapes

Of course, at some point the possibility of an external filter is exhausted. If you get into areas of 1000 liters and more, it is usually difficult to get suitable filters here. Then it is time to build special filter tanks. In specialist shops, these will usually only be available very rarely. Here we recommend the classified ads and advertising portals. The structure is usually realized with separate aquariums. Layers with different filter materials are then formed in these. On one side is the inflow of the water from the actual aquarium and on the other side the water comes back again. Of course, this also requires special high-performance pumps. Pond pumps are often used here. There are also various building instructions available online. We have also included a video for you here.

 

Another special form are the trickle filters. These are also rarely found today. This filter sits above the aquarium and contains its filter media there.

These are often also known as tube filters, where the filter media are stored in individual tubes.

 

Conclusion on the individual types of filtering

 

Before deciding on the right filter, you should ask yourself the following questions:

 

• How big is my aquarium?
• How strong is the trimming (depending on how often you have to clean the filter)
• What budget do you have available?
• Do you need a flexible filter? (change of filter media)
• Should it be an internal or external filter? Or maybe a combination of both?
• Which filter volume should the filter have?
• Would you like to assemble the filter yourself?

 

Depending on this, you have to choose the appropriate model.

 

Filter system recommendations

 

 

Determining the correct filter size - calculation of the filter performance

Now we come to an important point, which you should pay attention to before you go buy a filter. The trade offers a lot of models and usually the appropriate liter numbers where they can be used are noted on the models. After that, you can quickly make a pre-selection. If you want to be more precise, you should test the flow rate. Here you can take a dry run in a separate pool with a precisely defined content and thus stop the time. This is then extrapolated and thus has the filter performance per hour. The manufacturer's information usually refers to clean filters and it is therefore also important to note that the delivery line decreases.

 

Rough calculation: aquarium water / contents of the aquarium should be circulated twice per hour. You should also allow for a reserve of around 20 percent, since the flow is impeded by the different filter media.

 

 

 

Computer controlled filter technologies

Today, computer-controlled regulation has also found its way into filter technology. The aquarium, or rather aquaristics, is becoming more and more digital. Manufacturers such as Eheim are already making it possible to control the aquarium filter via USB with your computer and with the appropriate software. But what are the advantages and, above all, what can you set there?

Terms such as constant flow, bio function, stream function, automatic assumption adjustment, service monitoring, electronic error detection and 12-hour rhythm play a major role. The filter technology brings different things with it, which can be regulated electronically depending on the model.

There is an intelligence that recognizes the degree of cross-linking of the filter and gives you an indication of when the next cleaning is necessary. A very good function, especially before a holiday.

There are also regulations that adjust the flow rate depending on the degree of contamination of the filter. Here, the power is regulated fully automatically, so that no losses occur.

With the 12-hour bio function, a natural flow rhythm is simulated in the aquarium using different flow rates. A very good function, especially at night. It is similar with the stream function. A different passage is also simulated here, so that the fish are once more in turbulent water and then less again.

Finally, a video of what is already possible today with the appropriate filter technology. Always provided you bring the necessary budget with you.

 

Volume of the filter for the filter medium

Not only the flow rate is decisive, but also the volume of the filter. This is the only way for the filter to have enough surface area to allow an effective bacterial culture to develop. The content in liters must be large enough for this. A general size cannot be named here. Most of the time you can assume that the bigger the better. This is the only way for the bacteria to have room and the service life to be extended considerably.

 

 

Regular maintenance of the aquarium filter

Cleaning and care is also an integral part of an aquarium filter. The main thing here is to regularly monitor the function of the filter. If there are problems here, it can quickly lead to fish deaths.

 

You should therefore regularly check the following:

 

• Is the filter still working?
• Is the flow still correct?
• Check for tightness
• Is the surface movement correct?

 

If problems are found with the flow, the filter must be cleaned. Only clean water should be used here. No washing-up liquid and no other cleaning agents. Brushes of different shapes can also be helpful.

With an external filter, the piping does not have to be cleaned every time. There are usually devices on the filter that only the filter basket can be removed. Saves not only time, but also work. The hoses should of course be cleaned from time to time. However, a different interval is appropriate here.

 

Note the power consumption of an aquarium filter

The performance of the filtering must also be considered, especially when calculating the maintenance costs. Most new filter pumps get by with very little watts (20 watts or less), but since they run 24 hours and 365 days, a lot still comes together. Let's calculate the electricity costs based on a 200 liter pool. A filter with around 20 watts of power is usually required here.