CaribSea Aragamax Select Reef Sand (30 lb) – A premium aragonite sand substrate for marine aquariums and reef tanks. Composed of oolitic aragonite, this fine, sugar-sized sand naturally buffers aquarium water to maintain optimal pH and carbonate hardness. It’s pure and phosphate-free, providing an excellent habitat for burrowing creatures and a vast surface area for beneficial nitrifying bacteria. Aragamax Select’s clean, white appearance mimics tropical beach sand, enhancing tank brightness and promoting a healthy environment for live rock and corals.