nature's ocean bio-activ live aragonite 20 lb natural white reef aquarium sand #0 nature's ocean nature's ocean bio-activ live aragonite natural white #0 live sand 20lbs (grain size: 0.1-0.5mm). premium live aragonite sand for aquariums; collected in its natural environment and packaged in its natural state (u.s. patent #'s: 6,376,299 & 6,939,708); just place in tank, add saltwater (for best results use nutriseawater) then add fish, no waiting required; instant ammonia cycling; perfect for most applications (except undergravel filters) for best results use as follows: use a minimum of 1 pound of bio-activ live aragonite per gallon of saltwater. setup filtering system and allow it to circulate. during the first month, introduce no more than 1 inch of fish per 5 gallon of saltwater.