Shock Treatment

Contrary to what most people think, a strong chlorine smell is not an indication of too much chlorine in the pool but actually a red flag that a “super dose” may be required to correct the problem.

Shock treatment adds a larger than normal amount of oxidizing chemicals to pool water. This additional dose destroys organic contaminants and oxidizes ammonia and nitrogen compounds to rid the area of irritating chloramine odor and, if chlorine is used for the purpose, to sanitize the water. Many chlorine shock products also provide usage instructions for destroying algae and bacteria, which can be an added benefit. Shocking should be done with the pump and filter operating, but after sundown to avoid the loss of chlorine to the sun’s ultraviolet (UV) rays.

Superchlorination is another term that is sometimes used for shock treatment with chlorine products when 5 or more ppm of FAC is added. This mode of shock treatment—in addition to oxidizing undesired wastes—is used to rid the pool of algae and bacteria that might be hiding in filters and hard-to-sanitize areas. Superchlorination also gets rid of chloramine odor. Adding 10 times the level of combined chlorine or chloramines in the water achieves so-called breakpoint chlorination when there is enough extra chlorine to consume the irritating chloramines.

Basic Rules of Thumb

  • Always read and follow the manufacturer’s instructions.
  • Store chemicals in a cool, dry and shaded place.
  • Never mix different types of chlorine—add each to the pool separately.
  • Never mix chemicals together—add each to the pool separately.
  • Avoid breathing fumes or vapors.
  • Don’t buy more pool chemicals than you’ll use in a season – they lose effectiveness over time.
  • Make sure pool chemicals are inaccessible to children.