Made from natural silicate at a high temperature, suitable for both freshwater, saltwater aquarium and pond. Its stable chemical characteristics accord with the primitive living environment where micro-organisms live in. The diameter of micropores ranges from 60 to 300um which is very close to the pores of loose soil. The space structure is optimal for micro-organisms colonization and growth. The multi-porous structure provides a 6 to 8 times larger surface compared to other ordinary bio-rings. Its highly penetrative porous structure enables the aerobic nitrifying bacteria's nitrification and anaerobic denitrifying bacteria's denitrification. Functioning with physical filtration materials can prolong its life of durability. It is an ideal biological filtration material.