Blue Wave is the most trusted chemical brand online. Compare to brands such as BIOGUARD®, SUN®, GUARDEX®, AND PACE®. This fast-dissolving formula delivers immediate results and powerful 56% available chlorine. Premium quality granular keeps pool water safe and clean by eliminating dangerous contaminants without leaving cloudy water or residue behind. Pre-dissolve and add directly to pool water. Cannot be used in a chlorinator. 99.5% Sodium Dichloro-S-Triazinetrione.