Complete with Net Bag Adsorptive filtration is a process in which dissolved substances are captured by solid bodies such as carbon. These dissolved substances can be harmful to aquatic life. They are generally of chemical origin such as chlorine in tap water, alkaline residues of aquarium medication and even some dissolved metals. However the toxic substances accumulate and the absorption capacity of the carbon is limited. With all types of carbon, the effectiveness is limited to a short period of time. They must then be removed from the filter, to avoid having the adsorbed substances washed back into the aquarium. We recommend that carbon be used for short -term only and for a specific purpose. After the inital aquarium setup or to remove medications or additives, turbidity, water discoloration and odor. This product offers the highest adsorption. It is alkali activated, acid-washed, pH neutral, heavy metal free and formed in a special compression mold to perform a rapid, highly effective adsorption of harmful substances and residues of medication.