OF 3DM Pro-Filter Medium is a revolutionary mineral based beneficial-bacteria medium that incorporates the most advanced heating and multi-staged manufacturing techniques and technology to create this super macro-porous and tough biological filter medium. It’s recommended for aquarist seeking the ultimate aquarium biological filter medium. • Largest Effective Surface Area • Longer Water Retention Time • Improves Water Quality • Tough and Macro-Porous • Ideal Bacteria Conditions • Flaking of Bio-membrane • Environmentally Friendly • pH Neutral