Coral sand is a piece of coral or shell, with the characteristics of continuous release of calcium carbonate, with different particle sizes and various specifications. It can improve the adaptable water environment for ornamental fish and shrimps that like slightly alkaline and high hardness. At the same time, coral sand is rich in pore structure and can also be used as a carrier for biological to cultivate nitrifying in large quantities. It is a high-quality and practical marine natural filter material. It is perfect for both freshwater and saltwater aquariums and offers durable and reusable performance. Features -Color: Light Brown. -Material: Coral sand. -Size: About 30x14x3cm / 11.81x5.51x1.18inches. -A bag of ordinary bone 2-6cm coral sand 500g. -Can improve the adaptable water environment for ornamental fish and shrimps that like slightly alkaline and high hardness. -A carrier for biological to cultivate nitrifying in large quantities. -A high-quality and practical marine natural filter material. -Perfect for both freshwater and saltwater aquariums and offers durable and reusable performance -Not only a practical filter material, but also a good decoration in an aquarium or fish tank. Package list: 3 x bag of coral sand