What Is The Catch Of Modern External Fish Tank Filters

Modern aquaria in most cases can not do without filtering equipment, which provides the necessary water quality and minimizes the effort to care for the aquarium. To address these issues, manufacturers often advise using external canister filters, as the most advanced and convenient in daily use. Is it really?

What are the pros and cons of these devices:

Of the benefits can be noted:

– good filtration quality;

– the absence of foreign objects in the aquarium, except for the intake and exhaust pipes;

– the need for more rare maintenance;


As you can see, there are no minuses that would affect the quality of filtering in these devices. Manufacturers have learned how to effectively deal with the possible leakage of these devices with the help of modern materials, therefore, with proper user vigilance, they are minimized. However, the prices of these devices may differ significantly from the prices of the best internal filters. The difference sometimes reaches 10 times. Therefore, manufacturers are most profitable to sell these filters.

Also, having decided to purchase an external filter, it is worthwhile to attend to the issue of its placement, since devices of this type are very voluminous, so they are often hidden in a pedestal under an aquarium.

What Is The Catch Of Modern External Fish Tank Filters


What is a modern external canister filter? This is a device that is installed outside the aquarium and consists of a body containing all filtering materials. In short, any external filter consists of a pump and compartments with filter materials. The pump is usually a motor pump that provides continuous movement of water.

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Constructive arrangement of the motor pump:

– inside the main body;

– as a remote device and placed on the intake tube inside the aquarium;

More powerful filters use the internal arrangement of the pump. In this case, the water enters the canister by gravity, and is released into the aquarium by the pressure created by the pump. This provides a higher outlet pressure and allows water to be raised to a greater height. In addition, the location of the pump after the filter elements allows it to work with clean water and does not require frequent cleaning operations. This pump arrangement can be called classic, as it is used by many major manufacturers of aquarium equipment, such as Tetra, Eheim, Fluval and others.

What Is The Catch Of Modern External Fish Tank Filters


Less powerful and productive models can use an internal arrangement of pumps. This solution has significant drawbacks:

– foreign element inside the aquarium

– the pump is installed before the filter elements, therefore it is quickly polluted and requires periodic maintenance.

The adherent of such a layout of its external filters adheres to the firm Aquael.

The effectiveness of the external filter affects a whole set of factors. We list them:

  1. Performance.
  2. The volume of filter elements.
  3. Filtering fillers.
  4. The number of trays for filter materials.

What Is The Catch Of Modern External Fish Tank Filters

What Is The Catch Of Modern External Fish Tank Filters

  1. Performance – selected for a specific volume of the aquarium. When choosing a specific filter model, it is worth remembering that its value strongly depends on the installation option and the filter materials used, so you should have a certain margin.
  2. The volume of filter elements. Here everything is simple and operates according to the principle: the more the better. Of course, you should not neglect common sense and fasten a 20 liter canister to a 15 liter aquarium. But the main trend is this.
  3. Filtering fillers should be varied. This will provide a more complete removal of suspended and dissolved pollutants from the water. From this clause follows the requirements for clause 4.
  4. Number of trays for filtering materials should be sufficient so that you can organize a full and sufficient filtering. Usually their number ranges from 3 to 5. Preference should be given to models with a large number of them.
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External canister filters are completed with hoses and tubes for organizing the intake and return of water to the aquarium. In addition, the kit often comes with a flute, which is designed to spray water over the surface of the aquarium. It is necessary to saturate the water with oxygen.

Manufacturers can complete their products with filter materials or sell without them, allowing the consumer to choose the necessary materials. The first option is most suitable for beginners and people who for some reason do not want to understand the intricacies of the selection of filter elements. The second option is most suitable for enthusiastic aquarists with experience. However, it is worth remembering that the use of too dense materials can greatly reduce the performance of the filter, which will adversely affect its efficiency.

Manufacturers often position their external filters as devices capable of performing all three types of filtration: mechanical, chemical and biological. Mechanical filtration is carried out by passing water through a porous filter element, chemical – through a chemically active or sorbing material. But contrary to the statements of manufacturers for the implementation of biological filtration conditions are created far from ideal. Biological filtration is most effective under conditions of active oxygen supply and low water flow rates, which is not observed in canister filters. Most closely to these conditions are suitable models in which a large volume of the body is combined with low productivity, however, such models are not carried out mechanically by the best way. The most effective in terms of biological filtration can be considered external semi-humid filters, which we will tell you about in a separate article.

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Therefore, even acquiring an expensive external filter, you should not hope for a complete biological filtration from an external canister filter. However, it is worth mentioning that in terms of the efficiency of mechanical and chemical filtration, models with external execution bypass almost all internal models.