Blue Treasure Calcium Sand 5KG (2mm to 3mm) Blue Treasure Calcium Sand (5kg, 2-3mm) is a premium natural substrate enriched with calcium, designed for both marine and freshwater aquariums. Its fine grain size provides a safe environment for fish and aquatic plants, while the calcium content helps stabilize pH levels and supports the growth of beneficial bacteria. This sand enhances water clarity, promotes natural behavior in fish, and adds a bright, clean look to your aquarium. Perfect for reef tanks, breeding tanks, and decorative aquascaping setups.