Why do you need shock if you always have sanitizer within the proper range?

The first step in fighting bacteria in water is to keep the water in the pool balanced.  When the pool water is too acidic or too basic the sanitizer will have a harder time at destroying the bacteria in the water.  Balancing the pool water means adjusting the Alkalinity, Calcium, pH and Sanitizer levels and keeping them within their proper ranges.

The second step to combating the bacteria in water is to have the water sanitized by chlorine or bromine.  Whether you choose to use chlorine pucks or sticks, salt chlorine generator or a bromine feeder, the sanitizer’s job is to destroy the bacteria in the water.

But once the sanitizer has completed its goal what happens to the bacteria?  It stays in the water waiting to be removed.

The third step is to clean up the bacteria that has been destroyed by the sanitizer and remove it from the water.  Shocking or oxidizing the pool will remove the unwanted bacteria and free up the sanitizer so it works more effectively for you. 

Therefore, if the pool is clear and the sanitizer is within its proper range, it is still recommended to shock (oxidize) the pool once a week during pool season.  Spring and Fall are times when you can go a little longer between shock treatments due to those colder weather conditions. Despite the cold water and less frequent use, you will still want to continue to monitor the pool water and shock every 10 – 14 days as needed.