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What Is The Difference Between Free and Total Chlorine In My Pool?  

Free chlorine is present in a swimming pool or spa after the addition of liquid chlorine, chlorine tablets, chlorine granules or after activation of a salt electrolysis. 

The presence of free chlorine, in combination with a correct pH value, ensures that your water is clear and disinfected. 

 

The following concentrations of free chlorine must be respected and regularly measured (with the HI-701 , HI-96725 or HI-83326 photometer):  

  • indoor swimming pool: 0.5 - 1.5 mg / l 
  • outdoor swimming pool: 0.5 - 3.0 mg / l 
  • spa, jacuzzi or whirlpool: 1.0-3.0 mg / l 

 

If the concentration of free chlorine is too low, growth of algae, bacteria and viruses occurs. In other words, the bathing water will be cloudy or green and not disinfected. 

 

Too high concentrations of free chlorine are unhealthy due to the formation of trihalomethanes such as chloroform. Additional disadvantages are the discoloration of, for example, textiles and hair and the deterioration of, among other things, swimming pool foil and pvc pipes. If the Free Chlorine reading of your pool is above 5mg/L, it is not recommended to swim in it. 

 

From the moment free chlorine binds to the dirt particles in the water, it becomes bound chlorine. Bound chlorine is chlorine that is chemically inactive and does not contribute to your pool sanitising.

 

In other words, bound chlorine is a measure of the 'waste load' of the water. The maximum concentration of bound chlorine is 0.6 mg / l. At a low pH (<7), bound chlorine can cause an irritating smell with eye, nose and mucous membrane irritations as a result. 

 

The sum of free chlorine + bound chlorine = total chlorine.