Ocean Direct is different. This pure aragonite substrate utilizes patent pending Sea Breathe laser technology to allow efficient respiration right in the bag. This method preserves real live sand with its own original, natural bacteria. Every bag of Ocean Direct is alive and breathing with up to 1000 times more beneficial water purifying bacterial than other preservation methods. Every grain of Ocean Direct is coated with bacteria and encapsulated, by capillary action, in a film of real ocean water. The thin film is open to the atmosphere for unparalleled gas exchange. This results in high counts of natural and beneficial bacteria with no noxious buildup of metabolic by-products. Each bag contains a packet of Bio-Magnet clarifier to reposition any free floating bacteria to where they are most active: sand beds, live rock surfaces, and biological filtration media. Ocean Direct gives you a thriving, natural aquarium in minutes! The 40 pound bag of Ocean Direct Caribbean Live Sand has a typical grain size between 0.25 mm and 6.5 mm and features an average density of 87 pounds per cubic foot.