Fluval BIOMAX bio rings have a complex pore system creating an optimal environment where beneficial bacteria can thrive. They have more capacity than most biological filter media and allow ideal water movement throughout the media to ensure optimal contact time for efficient biological filtration. BIOMAX also reduces and controls ammonia and nitrate. Key Features : *Biological filter media *Supports thriving beneficial bacteria growth *Reduces and controls ammonia and nitrite *More efficient than most biological filter media *Replace every 6 months *Convenient 1,100 g (38.80 oz) format *Ideal for use with most canister filters *For use in freshwater and saltwater aquariums