<p>All Sand and Gravel pics are sized 1 to 1</p><p> #00020 (15 lb)</p><p> #00050 (40 lb).</p><p>Seaflor Special Grade Reef SandTM From CaribSea</p><p>1.25 - 1.95 mm diameter grain size. A revolution in reef-keeping! This is the one you've been reading about in all the hobbyist publications. This grade of aragonite is specifically engineered for plenum-type nitrate reducing beds or anywhere a deeper bed is called for. The pore water space created by precision grading also allows maximum pH support and dissolution of calcium carbonate. </p>