Adding shock to your pool removes contaminants that cause poor water quality. When you add a shock treatment to your pool, you remove contaminants that cause cloudy water, chlorine odor and eye irritation - not to mention preventing future problems and reducing the need for other chemicals. Shock Xtra Blue® is a 6-in-1 shock that give the extra benefits of killing algae and bacteria. Shock Xtra Blue® is a fast dissolving shock that creates sparkling water. Formulated to allow you to swim in as soon as 15 mins after treatment.