Deep Blue Professional DB Nitrate Pad 18x10" Cut to fit media pads traps micro and macro organic particles, foreign debris, and excess fish food. For use in custom sumps/refugiums, hang-on filters, prefilter boxes, and more. Safe for both freshwater and marine aquaria.            Chemical & Mechanical  Dual stage filtration Safely reduces nitrate levels Promotes a healthy aquatic environment. New thicker, more rigid design for extended use.