Biological aquarium filtration is a complex process essential for clean, healthy water. Purification bacteria in the filter make sure that pollutants such as fish waste are being broken down biologically. They require a filter medium on and in which they can settle to fulfill their task. However, the filter medium must meet some criteria to make it optimally suitable for being settled by purification bacteria.
The optimal surface structure
The filter medium must provide a certain surface structure as to allow purification bacteria settling on and in a filter medium. The bigger the surface, the smaller the pores. Above a surface of approximately 450 m² per liter, the pores are so small that no bacteria can grow in them anymore. As proven in a university study, 270 m² / l is the optimal settling area, since the pore size then exactly corresponds to the size of the bacteria and the bacteria thus can settle ideally. sera siporax provides exactly this surface.
sera siporax is made from a mixture of recycled glass powder and salt crystals of an exactly defined size. The size of the salt crystals exactly corresponds to the the size of the bacteria – that is particularly important since thy define the pore sizes as placeholders. The mixture is pressed in ring shape and sintered, that means burned, at approximately 780 °C (1436 °F). The rings are then washed out, removing the salt crystals and leaving the pore structure behind.
Quality criterion No. 1: Porosity
The porosity described above is the first quality criterion that characterizes a good filter medium. This property is very easy to check: in case of sera siporax, cover the ring with a finger and blow through it. Due to the open pore structure, the air passes through the outer walls of sera siporax. On the contrary, ceramic rings, for instance, have closed pores that do not allow air to pass through the wall.
Quality criterion No. 2: Connectivity
Connectivity is the second quality criterion. Under a microscope it can be seen that sera siporax has an open pore structure and that the pores are connected among each other. In comparison, ceramic, for instance, has many pores, which however are not connected among each other. Sphere shaped filter media have very fine pores, but they have the disadvantage that they do not allow for water flow. They can therefore not be settled inside. Furthermore, the pores are too small to allow for an optimal settling area for bacteria.
The absorption test shows that the interconnected pore structure of siporax absorbs the liquid much quicker than, for instance, ceramic. A similar test with a highly viscous liquid proves that the liquid – and correspondingly also the bacteria – can enter up to the inner ring wall only in case of sera siporax. Filter media made of ceramic and sphere shaped filter media, on the other hand, are only being settled at the surface.