NST is an alternative to 3″ tablets and does not contain cyanuric acid. Perfect for use in a skimmer, this product will destroy bacteria and organic contaminants without over-stabilizing your pool by adding additional cyanuric acid to your water. Each long-lasting tablet will continuously sanitize your pool in the skimmer for up to one week! This product is an innovative, proprietary technology that provides long-lasting, slow-dissolving chlorination sanitization levels.