Experience nature s benefits! Nature s Ocean® Premium Aragonite Reef Substrates 20 lb. are ideal for reef system tank bottoms and denitrifying anaerobic beds. With an extremely high surface area filter media it will increase Carbonate Hardness and reduce Nitrates 100% from the ocean floor helping to maintain pH and provide marine trace elements. Heat sterilized and perfect for culturing live sand it is recommended to use at a rate of 10 lbs per square foot of the tank floor s bottom area offering a 1 deep covering. Depending on your needs the depth may vary from 1/8 - 3 . With a variety of options including ARAGONITE SAND #0® ARAGONITE SAND #1® and ARAGONITE GRAVEL #4® you ll enjoy beautiful color and size gain.