Milky or Cloudy Water

You may have milky or cloudy water with suspended particles present? 

You have trouble seeing the bottom of the pool?


The development of milky or cloudy water can be due to several factors:

  • Your pH is not right
  • The quantity of disinfectant (chlorine, bromine, etc.) in the water is insufficient
  • The filtration time is not suitable
  • You are encountering an over-stabilisation issue


  • Your pH is not right:
  • If the quantity of disinfectant (chlorine, bromine, etc.) in the water is insufficient:
    • Apply a shock treatment with hth®  SHOCK® Powder
    • Use hth® RAPIDFLOC®, a liquid flocculant for sand filters, which will clarify the water by precipitating impurities to the bottom of the pool. To be used with the filter switched off. 
    • Then backwash the filter several times and let it run continuously for 24 to 48hrs. This action will significantly improve the filtration quality and thus, help maintain crystal clear water
  • If the filtration time is not suitable:
    • Adapt the filtration time to the water temperature according to the following calculation: 
      Water temperature / 2 + 1 hour.
    • Preferably run your filtration during the day rather than at night
  • In the event of over-stabilised water:
    • Check the stabiliser content; if it exceeds 80 ppm, you need to partially or fully empty out the pool:
      From 80 to 120 ppm: ½ the pool
      Above 120 ppm: ¾ of the pool
  • Use hth® STICK® (non-stabilised chlorine) as a regular treatment to avoid over-stabilisation.


To prevent cloudy water and improve filtration fineness, hth®  REGULARFLOC improves the day-today filter fineness of pools with sand filter.