HTH 59419 Super Shock and Swim Powder for Swimming Pools, 1-Pound, 10-Pack (Discontinued by Manufacturer)

Destroys organic contaminants and restores free available chlorine to the water. Shock treating your pool weekly is important because it protects you and your family from bacteria and organic contaminants. Super chlorination or shock treating removes chloramines, which cause eye irritation and "chlorine" odors from the pool water by adding free available chlorine (FAC). We suggest shocking at the same time and day each week. Sundown is the best time to shock your pool because the chlorine can work without fighting the sun's UV rays. Shocking after sundown also gives chlorine more time to restore water clarity. In some cases, you may need to shock more than once a week.