We are often asked this question especially by new pool owners. The purpose of shocking your pool is to kill the algae, bacteria and organic compounds. Shocking your pool is mostly undertaken for the following reasons:
When the bather load on your pool is at its peak.
After heavy rain or high winds.
When chlorine testing shows your free chlorine is low.
The downside to shocking is that you limit the time you can use your pool as you’ll need to wait until the chlorine concentration in your pool returns to 3-4 parts per million. Your testing strips will let you monitor this easily.
What is Pool Shock?
Pool shock is chlorine or non-chlorine chemicals that you add to your pool water to destroy any algae, bacteria and organic compounds that are not being handled by your normal day to day water treatment system.
There are two types of chlorine in your pool. Total chlorine and free chlorine. Free chlorine is the chlorine that is available to “attack” and kill bacteria, algae and organic compounds. Total chlorine is the combination of the “attack” chlorine and the chlorine that has bound to and killed algae, bacteria and organic compounds after killing it.
Why Do I Need to Shock My Pool?
There are two ways a pool is contaminated. People and Mother Nature. Every time we jump in a pool we introduce, saliva, skin cells, urine, lotions and potions and may other things. Every time the wind blows, trees drop their leaves or it rains Mother Nature introduces organic matter into your pool.
These contaminants act as a food source for algae and bacteria and this is why we have to treat our water with sanitizers which attack and kill algae, bacteria and organic compounds.
Remember though that if you are diligent and ensure your pool chemistry is well maintained you will reduce the need to shock your pool. However if you let your chlorine or alternative sanitizer levels drop too low you will need to shock your pool to ensure a safe swimming environment.
What is My Chlorine Test Measuring?
Chlorine testing usually measures free chlorine ie the “attack” version of chlorine and total chlorine ie the chlorine that has already attacked and killed the algae, bacteria and organic contaminants.
Total chlorine and free chlorine should be equal. This shows there are enough reserves of the “Attack” chlorine to hit any new algae, bacteria and organic matter