Carib Sea ACS20821 Instant Aquarium Tahitian Moon Sand, 20-Pound, 2 Per Case Water Packed With Living, Water-Purifying Bacteria, State Of The Art Clarifier And Complete Water Conditioner. Detoxifies Metals, Eliminates Ammonia, Neutralizes Chlorine And Chloramines, And Provides A Protective Slime Coat For Fish. Also reduces nitrates and nitrites. Simply Add Tap Water And Instant Aquarium Automatically Begins The Cycling Process.