The Xport-NO3 Cube is designed to be used in marine and hard freshwater aquariums with a pH of 7. 5 or over. This denitrifying filtration media eliminates the need to perform water changes that are carried out for the express purpose of decreasing nitrate in an aquarium system. The Xport-NO3 cubes utilize NanoIntelex Technology to create an enhanced, "ultra-activated" material with the capacity to outperform conventional denitrification media by over 300%. Provides over 71, 000 square feet of usable surface area per liter of cubes. This leads to higher efficiency results in smaller space requirements to achieve equivalent denitrification. May be used in conjunction with Xport Bio Cubes and Xport PO4 cubes filter media.