Sand is the oldest and most popular method of filtration, and you want to ensure you use the best sand possible for your pool. #20 Grade Silica Sand is perfect for keeping your pool sparkling clean by trapping debris down to 20 microns within the sand. This debris is easily purged with a simple ‘backwash’, which we recommend to do weekly. Silica Sand gives you up to 7 years of clean, sparkling pool water.