Soil filter
The bottom filter is an internal filter used in freshwater aquariums .
functionality
This filter uses the substrate in the aquarium (mostly gravel) as filter material. The following method is widely used: Before entering the substrate, close-meshed screen elements are installed on the ground so that a free space is created between the ground and the gravel substrate. These filter elements are connected to a pump ( air pump for small pools ) with a riser pipe , which draws the water down through the gravel ground, conveys it upwards and feeds it back in. Fine gravel acts as a water filter and can remove cloudiness caused by suspended matter.
Biological effect
A floor filter promotes the exchange of the water in the basin by its surface. Due to the position of the filter material, sludge and animal excretions are quickly fixed in the ground and partially biodegraded by bacteria. If the gravel is too coarse (too small a surface for bacteria to colonize), the effect remains weak.
Advantages and disadvantages
The low space requirement, the low price and the modest technical effort speak in favor of this filter method. However, it is only recommended for tanks that are not too large and not too demanding animals. However, this is contradicted by the fact that the basin contents can hardly be varied by using gravel as the substrate. In addition, changing or cleaning the filter material is hardly possible without emptying the basin. At best, superficial cleaning is only possible with a sludge bell, which can quickly shake the biological balance of the filter. The filter is almost useless for large aquariums, as many riser pipes would have to be attached here. The vertically operated Hamburg mat filter requires less maintenance and delivers better results than the gravel floor filter.