• A choice of  densities allow for step-wise transition from mechanical to biological filtration.
• Excellent surface area per sq. ft. with good adhesion of nitrifying bacteria.
• A high number of interstitial spaces in the tri-dimensional matrix of the filter media improves an early and even growth of bacteria.
• High free volume for smooth, even water flow throughout.
• 3-Pack, featuring Black, Green and Blue filter mats.
• Each filter mat measures 12" x 12" x 1.5" thick.