Aquarium Biofilter Media Pack: Mix 15 filter biological media: 500 g x 2 packs (2.2 lbs). All biofilter media are housed in 2 zippered mesh bags. Including the perfect combination of bioceramic rings, porous ceramic biospheres, biochemical balls, quartz beads, medical stone and other aquarium biological media. Ceramic Bio Ball, Bio Ring: Ceramic biological media are fired at high temperature, and their surface and interior are covered with small pores, It provides an environment for the growth and reproduction of beneficial nitrifying organisms. These complete biological nitrification systems can effectively improve water quality microcirculation, Enhance metabolism and increase fish energy. Medical stone, volcanic stone, activated carbon: Medical stone and volcanic stone contain a variety of minerals and trace elements. Provides essential minerals for fish growth while cultivating beneficial organisms. The matching activated carbon can purify the water, remove the odor of the fish tank water, and make the water clearer. About using: Before use, please take out the black columnar activated carbon from the mesh bag, pour it into the mesh bag, close the zipper and rinse it with water. After cleaning, put it in the filter. Try not to flip the biological medium at will during work to avoid other media from adhering to the black color. (If activated charcoal will not be used, it can be removed) Reminder: Ceramic biological media will be upgraded and improved with market demand, and the types may change in the later stage. If you have any media you like and which you don't like, please email us and let us know, we will take the advice of most people to match your favorite biological media!