The advanced Tetratec® BF Biological Filter Foam is designed to be used with the Tetratec® EX 600 and EX 700 External Filters. The highly advanced biological foam provides a large surface area for the growth of beneficial bacteria 

The advanced Tetratec® BF Biological Filter Foam is designed to be used with the Tetratec® EX 600 and EX 700 External Filters. The highly advanced biological foam provides a large surface area for the growth of beneficial bacteria