Dymax Bio-Glass is made from natural silicate at a high temperature, suitable for both freshwater, saltwater aquarium and pond. Its stable chemical characteristics micro pores size (from 60 to 300um) makes it ideal 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.