Deep Blue Professional ADB41005 Nitrate Remover Pad, 18 by 10-Inch Nitrate remover cut to fit media pad 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 Safely reduces nitrate levels Measures 18-inch length by 10-inch width