Calculate how much pool shock (calcium hypochlorite or dichlor) to add to super-chlorinate your pool. Break chloramines and sanitize effectively.
Enter your pool volume to calculate the required shock dose to super-chlorinate your pool to 10 ppm free chlorine. Shock treatment breaks chloramines and kills resistant algae.
Always shock in the evening or at night. Daytime sunlight rapidly degrades unprotected chlorine (shock does not contain CYA stabilizer).
Wait until free chlorine drops back to 1-4 ppm before allowing swimmers to enter (typically 8-24 hours). Pre-dissolve shock in a bucket of water before adding.
Pool shocking (superchlorination) involves raising the free chlorine level to 10 ppm or higher to break down chloramines (combined chlorine), kill algae, and eliminate bacteria and other contaminants. It's necessary when the pool smells strongly of chlorine (a sign of chloramines), after heavy use, after a storm, or when algae is present.
Shock your pool: after heavy bather load (parties, etc.), after a storm or heavy rain, when you detect a strong chlorine smell (chloramines), when algae appears, when combined chlorine exceeds 0.5 ppm, or as a weekly preventive treatment during peak swimming season.
Always shock in the evening or at night. Daytime sunlight rapidly degrades unprotected chlorine (shock products typically don't contain CYA stabilizer). Shocking at night allows the chlorine to work overnight and reach safe levels by morning.
Calcium hypochlorite (cal-hypo, 65-78% available chlorine) is the most common shock product. It raises calcium hardness and has a high pH. Dichlor (56-62% available chlorine) contains CYA stabilizer and has a neutral pH. Cal-hypo is generally preferred for regular shocking; dichlor is useful when you also want to boost CYA.
Wait until free chlorine drops back to 1-4 ppm before allowing swimmers to enter. This typically takes 8-24 hours depending on sunlight, temperature, and the amount of shock used. Always test before swimming.