C.L. Industries 3045-50O 50 lb Silica Sand Stucco Bag 30/45 - This sand contains silica, which is finely broken down quartz stone. The rough and coarse sand is able to improve water quality over long periods of time by slowly removing pollutants such as dirt, hair, leaves and others. This process ensures that the pool water is clean and healthy, and ready to be enjoyed year-round.