6 lb./2 gal Pail Aquarium Blend Charcoal, Granular Activated Carbon for Aquariums, removes toxins, Water Purification Our Aquarium Blend is the same granular activated carbon used by the largest manufacturer of aquariums in America. Its unique meso-pore size distribution removes colors (tannins), dyes, odors, medication (antibiotics), dissolved organics, heavy metals, chlorine, other toxic compounds, leaving your aquarium smelling fresh and and crystal clear. This is a granular activated carbon produced by a high temperature steam activation process under stringent quality control. It has a large surface area, high mechanical hardness, unique pore size distribution, low density and chemical stability. Recommended filter grade carbon for aquarium water purification. This is a coal-based activated carbon.