Caribsea Aragonite Reef Sand 15lb / 6.8kg Caribsea Aragamax Aragonite Reef sand, sea floor special grade is a calcium-rich aragonite marine substrate, packed with beneficial bacteria. Sea floor special grade is ideal for deep beds, plenum systems, reef or fish tank bottom cover. Approx 1-2m diameter Caribsea aragonite helps to create a natural biological and mineralogical balance to discourage nuisance algae growth and promote healthy fish and invertebrates. Controls Nitrate, Nitrite, Ammonia and other wastes. Unsuprassed buffering capability, helps maintain a proper pH of 8.2 without the constant addition of chemicals. Incredible surface area for water purifying bacteria, upto 100,000 square inches of surface area per pound! High in strontium, magnesium, and other trace elements essential for coral growth and always silica free. Environmentally responsible - not beach or reef zone collected. For deep beds use 2lb per gallon, for shallow beds use 1lb per gallon. Suitable for marine tanks, not for use in freshwater aquariums.