API BIO-CHEM STARS are a biological filter media that provide a home for growing massive colonies of nitrifying bacteria to establish and maintain a healthy aquatic ecosystem. The nitrifying bacteria convert harmful ammonia into nitrate. This is called the nitrogen cycle, and it occurs naturally in all underwater environments. Your fish will produce waste, which fuels the growth of the beneficial bacteria that will comprise your biological filter. These bacteria continue to grow as your aquarium ages living on the top layers of the aquarium gravel, or in filter media such as API BIO-CHEM STARS. Formed under a patented production process that creates a 50-70 micron internal pore network. This pore size is optimal for the growth of beneficial, nitrifying bacteria that remove toxic ammonia and nitrite. Space-age porous polymer allows for rapid transfer of oxygen and water which keeps bacterial colonies healthy and active. Due to their design, API BIO-CHEM STARS achieve 4 times more surface area to colonize bacteria than ceramic rings. DIRECTIONS FOR USE: Rinse thoroughly to remove any dust. Place BIO-CHEM STARS in the last compartment of your filter. BIO-CHEM STARS will become colonized by bacteria within several weeks. Using API STRESS ZYME will help with the development of the biological filter. SIZE: 20 count