Seachem Matrix is a high porosity biomedia that provides efficient biofiltration for the removal of nitrogenous waste. Matrix™ is a porous inorganic solid about 10 mm in diameter. Each liter of Matrix™ provides as much surface (>~700 m2) as 170 liters of plastic balls! Plastic bio-materials provide only external surface area, whereas Matrix™ provides both external and internal macroporous surface area. These macropores are ideally sized for the support of nitrifying and denitrifying bacteria. This allows Matrix™, unlike other forms of biomedia, to remove nitrate along with ammonia and nitrite, simultaneously and in the same filter.
Matrix™ is completely inert and will not breakdown. It need not be replaced. Since the majority of the bacteria are internal, Matrix™ may be rinsed when needed without damaging the filter. Matrix™ is compatible with all types of wet or wet-dry filters.
Use 250 ml of Matrix™ for each 100 litres of water. Matrix may be placed in any kind of filter, and is particularly effective in a canister filter. Matrix is sufficiently large that no filter bag should be required for most applications.
Surface Area of Matrix, Eheim Substrat Pro, and JBL MicroMec
Two competitors, Eheim (Substrat Pro) and JBL (MicroMec) have advertised their own biological filter media (in both cases, sintered glass) and are claiming larger specific surface areas than Seachems claim for Matrix.
For biological filter media, specific surface area (measured as surface area per gram of material, or surface area per some specified volume of material) is very important. These products provide surface sites for bacteria to attach and do their work. The greater the surface area per gram of medium, the greater the number of bacteria that can attach. Thus a high specific surface area is desirable.
There is a second consideration, and that is the size of the pores in the medium. Generally, with very large pore diameters, we have smaller specific surface area, so that is not good. This generally rules out pores above 10 microns in diameter. But we can go too far in the other direction. If we have a very large number of very, very small pores, then our specific surface area number will be phenomenal, but the medium will not work very well as a biological medium. This is due to physical limitations, specifically too small a volume to support bacterial growth, and the decreasing efficiency of fluid transport (necessary to carry nutrients to the bacteria and waste away from the bacteria) with very small pore sizes. (Small pores still play important roles in physical and chemical processes, such as adsorption.)
BET surface area measurements indicate that Matrix™ contains nearly 10 times the specific surface area of Substrat Pro, and more than 20 times the specific surface area of MicroMec. Practically all the specific surface area of both Substrat Pro and MicroMec are in the range of pore diameters to be biologically useful, while some of the surfac