Green Water

How to correct green water in your pool ?


Your water has turned green, the walls are slippery and covered with algae, as well as the bottom, around the skimmer, outlet nozzles and/or the steps?

Algae has developed in your water. There may also be phosphates present. Green water can also be due to poor water treatment: pH not properly adjusted, insufficient filtration time, not enough disinfectant (chlorine), over-stabilised water, etc.

What is the treatment for green water?




  • Brush the pool walls and skimmer basket 
  • Adjust the pH to between 7.0 and 7.4 with hth® ​pH PLUS or hth®  pH MINUS
  • Apply a shock chlorination treatment with hth®  SHOCK® Powder
  • Wash and rinse the filter 
  • Let the filtration run during 24hrs
  • Place one or more hth®  REGULARFLOC® flocculant cartridges in the skimmer
  • Use a concentrated anti-algae product: 
    • To protect your pool and fight against the proliferation of common algae, use hth® SUPERKLERAL®, a non-foaming anti-algae product especially adapted to turbulent water (powerful filtration, counter-current system, jets, etc.)
    • Certain types of algae found in swimming pools, such as black or pink algae, are especially resistant, even to chlorine. In this case, use hth® BLACKAL® SHOCK, an effective treatment thanks to its copper-based formula.
    • For the curative treatment of mustard algae, use hth®  YELLOW SHOCK
  • 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® ADVANCED® (non-stabilised chlorine) as a regular treatment to avoid over-stabilisation.
  • Phosphates are the main source of nutrients for algae. Regularly check the phosphates level in the water and treat the water if needed with hth® ANTI-PHOSPHATES