Charcoal House 5 Gal Pail of Aquarium Blend, Granular Activated Carbon (coal based) for aquariums, Fish Tanks, unique meso-pore size distribution, clear water, remove odors, 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.