Xport BIO Blocks boast ultra-porous ceramic for biological filtration, offering superior performance! Designed for marine and hard freshwater aquariums with pH of 7.5+, Xport provides outstanding porosity and surface area, with lab-tested results of 40,000 square feet (3,716 square meters) of surface area per liter! One 2” block offers around 10,000 square feet of usable bacteria surface area, while 1.5” blocks provide around 4,000 square feet. With proper colonization, and use as directed, these blocks reduce ammonia and nitrites to near-zero, phosphate significantly, and dissolve organics. Incredibly versatile, Xport can be the sole filtration medium or combined with other media; care instructions provided. Doped with Aragonite to buffer pH, and available in 1.5” and 2” sizes in various pack sizes. Be inspired by this cutting-edge technology!