The Best Internal Filter For Aquarium

In continuation of the article on the organization of filtration in an aquarium, I propose to discuss one of the types of filters – internal filters.

So, as the name implies, internal filters are filters that are located inside the aquarium. The classical design assumes the presence of a filtering element and a motor pump, which sets water in motion. Structurally performed in a single package or have a modular design. Such filters fall under water and are installed on one of the walls of the aquarium. You can read more about the options for installing internal filters in the article at the link.


In most cases, the simplest designs are made of two parts – a pump and a glass with a sponge. The sponge performs the function of the simplest filter, performs mechanical trapping of impurities and suspensions in the water, and also becomes a place for the settlement of bacteria participating in the nitrogen cycle. It is fair to say that sponge sizes are often very small to make any significant contribution to biological filtration. Such designs have good mechanical filtration and decent performance, which really decreases as the filter element gets dirty. The developed competition among manufacturers of similar devices makes them invent new designs and introduce various technical innovations. In support of this statement, the internal filters began to be equipped with nozzles for aeration, flow rate regulators, and swivel heads. There were designs for cherepashatnikov aquaterrarium and which can operate at very shallow water level or horizontal position.

The Best Internal Filter For Aquarium

Multiple Filters

The most advanced designs among the internal filters can be considered multisectional and modular designs. There are several compartments for filter elements that can be filled at your discretion. Manufacturers usually offer two compartments that are initially filled with either two sponges, or a sponge and ceramic rings. The use of two sponges is justified by the possibility of cleaning them one by one, which has less effect on biological equilibrium, and the use of ceramic rings as a substrate for microorganisms in the internal filter causes a lot of controversy, since the conditions for biofiltration on a small amount of this filler washed by a powerful stream of water are far from optimal . Someone even declares that it is impossible to combine effective biological and mechanical filtration in the internal filter, since the optimal course of these two processes occurs under different conditions. True multisectional and modular filters have larger sizes than simple internal filters and, therefore, take up more space in the aquarium. Therefore, before buying it will be reasonable to check the overall dimensions of this device and compare them with the size of your aquarium.

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Use of pump circulators

Often in aquariums used constructions made of pump-circulators. To do this, separately purchased such a motor pump, in which the water inlet has a long grid intake tube. A sponge of the required shape, size and density of the structure, which is put on this tube, is also bought or made independently. As a result, we get a ready-made filter with a filter element volume that is much larger than that set by manufacturers in closed glasses. True, such a solution also has disadvantages, among which is an unaesthetic appearance. After all, all the pollution, detained by the filter and settled on the sponge, are outside and are clearly visible when watching the aquarium. It is also worth mentioning that when removing the filter from the aquarium to clean it, some of the dirt is washed off the sponge and goes back into the aquarium.

The Best Internal Filter For Aquarium


Any internal filter requires periodic maintenance, as various pollutants accumulate over time, the filter element clogs with them, and productivity gradually decreases. If you let this process take its course and do not control the degree of contamination, then over time the filter stops altogether. For cleaning about once a week, the device must be completely removed from the aquarium, however, recently there have appeared such designs that allow you to clean the filter element without removing the pump from under the water. Here, the advantage is kept by closed glasses, which keep well all the filtered dirt inside and do not allow it to spill back. The filter element and the rotor chamber are cleaned. This procedure is better to combine with the replacement of water in the aquarium, as the washing of the sponge should be done in the drained water. It is not necessary to wash it under the tap, and also strive to wash clean. It will be enough to perform two or four weak compressive-unclenching movements. By this we minimally damage the microorganisms inhabiting it.

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Bottom filter

One of the variants of the internal filter is the bottom filter. It is a perforated plate, which, when starting the aquarium, is laid under the soil layer and forms free space under it. A tube passes through the plate, connected to the motor pump, which causes water to seep through the ground, where all the dirt is deposited. The inventors of this design believed that the use of a large surface area, which has aquarium soil, will allow to organize an effective biofiltration. However, in practice it turned out that it is impossible to provide a uniform flow of water through the entire bottom surface, therefore only the part located close to the water intake pipe works according to the designed scheme. In addition, the constant infiltration of water leads to the leaching of nutrients from the soil into the water where they can easily be consumed by algae. Higher plants in such a situation are left without the necessary elements and live "on a starvation diet." Also, these bottom filters impose requirements on the size of the soil particles, which must be large enough not to leak through the perforations in the plate. Failure to comply with this requirement can lead to very fast pore clogging in the plate and stopping the flow of water. And if you add the impossibility of cleaning it without a complete disassembly of the aquarium, it becomes obvious that the use of this type of filters in modern aquariums is not justified.