What Does It Mean To Shock A Pool Or Hot Tub?

Despite how it sounds, to shock a pool or hot tub does not have anything to do with electricity. The process actually involves simply adding chemicals to your pool.

There are many reasons why shocking a pool is necessary which will be covered in more details in the article below.

hot tub shock

Why Do We Shock Our Pool?

Shocking usually makes use of chlorine to achieve the results below:

  • Break apart chloramines or commonly known as combined chlorine.
  • Kill bacteria, algae, and other toxic pathogens.
  • Quickly increases the chlorine level of the pool.

Shocking is also done to tackle combined chlorine. In a pool or hot tub, there are three measurements of chlorine which include free chlorine, combined chlorine, and total chlorine as explained below:

  • Free Chlorine – It is free to interact with algae, bacteria and other chemicals. It is good as it can kill harmful pathogens during interaction.
  • Combined Chlorine – Chlorine that is stuck with nitrogen or ammonia can no longer interact with other particles in the water which makes it an ineffective sanitizer.
  • Total Chlorine – It is a mixture of both free and combined chlorine.

When a pool is shocked, the combined chlorine is released which then off-gasses contaminants and increases the amount of free chlorine in your pool or hot tub.

If the level of total chlorine in your pool is high, a non-chlorine shock is needed. If its level is low, a chlorinated shock is to be used.

As a rule, the level of free chlorine needs to be increased to at least 10 times of the level of combined chlorine before the “break point” can be reached.

When Do We Shock Our Pool?

Shocking needs to be done in a variety of instances and they include the following:

  • After a pool or hot tub party when the additional load of bathers adds extra strain on the chlorine inside the pool.
  • After or during hot days of the summer. The sun boils the chlorine out of the water and this triggers the growth of bacteria and algae at a highly rapid rate. Since algae is a plant, it grows excessively with the presence of sunlight.
  • After or during a period of excessive rain which often increases the pH of the pool. When the pH is out of balance, the chlorine does not work as effectively. In addition to that, when rain falls, it mixes with contaminants such as pollutants and pollen which get dumped into the pool. Heavy rain may also cause ground runoff to enter your pool.

Pool Shocking Guidelines

  • Do not shock the pool if its combined chlorine level is at .5 or above.
  • Shock-up is to be added against the wind direction to protect your eyes and face.
  • Do not add water to the shock; always add shock to water.
  • Do not swim right after shocking and follow proper instructions after every shock.
  • Do not cover the pool or hot tub when chlorine levels are below 5 ppm.
  • Shock needs to be limited to 7.2 to 7.4 pH levels.
  • Leftover shock must be disposed of.

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