Difficulties with water care with whirlpools

Difficulties with water care with whirlpools


Very small amount of water
Due to the small amount of water there is a very high concentration of dirt in the water. When 3 people go into the whirlpool, the load is the same as when 150 people go into an 8 x 4 m swimming pool.

Very high water temperature
A Jacuzzi is operated with 35 to 38 °C warm water. This is the optimal temperature for bacteria. One bacterium can become 1 billion bacteria in 10 hours at these temperatures.

Very small filter systems in the whirlpool
Compared to the pollution of the water, the filter systems are undersized and the filter running times are often much too short. As a result, the dirt remains in the spa and must be chemically cleaned.

A strong turbulence of the water
Due to the strong turbulence of the water, the carbon dioxide in the water is outgassed and this can lead to lime precipitation. The turbulence also causes many disinfectants (such as chlorine) to decompose more quickly.

The three biggest enemies when disinfecting water in the whirlpool

Limescale precipitation

  • Lime and carbon dioxide are always in the water.
  • They are chemically bonded and dissolved in water.
  • A lot of carbon dioxide + a lot of lime in the water = hard water.
  • Due to the heating and turbulence of the water, carbon dioxide is released and the dissolved lime is transformed into limestone: Limestone is deposited in the inner walls of the pipes. A whirlpool with 50 nozzles has approx. 100 m of piping with an inner surface of approx. 150 m². They can be completely covered with limestone. This keeps bacteria in place and fats settle. The bacteria multiply and form a biofilm.

Fats, oils and cosmetics

  • They originate from the skin and get into the water despite previous showering.
  • They form thousands of the smallest invisible drops in the water.
  • These drops get stuck on rough surfaces and accumulate there.
  • At the interface of the drops, between oil and water, bacteria accumulate.
  • The bacteria use the oils as a food source and form a biofilm.
  • Oils and cosmetics are very difficult to oxidize with disinfectants: high dosages are necessary.


  • Biofilmsare a survival strategy of bacteria.
  • They settle down and produce a mucus of polysaccharides.
  • The biofilm protects the bacteria from disinfectants such as chlorine.
  • Biofilms are formed in the pipelines, on free-floating oil drops, in the filters.
  • 95% to 99% of the bacteria live in the biofilm. Only 1% to 5% of the bacteria in the whirlpool can be killed with classic disinfectants.
  • Biofilms grow permanently and develop very quickly.

Imagine not brushing your teeth for three days. The coating you can then feel is a biofilm.


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