When should you shock your swimming pool?You should shock your pool once a week, or at least once every other week to help maintain sanitized water. The more often you use the pool, the more often you should shock.But when is the right time to add shock? The answer: at night. Chlorine pool shock is unstabilized, and the sun will burn off the chlorine before it has time to do it's job. To get the most out of your shock treatment, wait until the sun goes down before shocking your pool.