• pH too high
• Insufficient amount of disinfectant
• Insufficient filtration
• Presence of limescale (hard water)
• Sur-stabilisation

pH too high 

• Lower the pH to between 7.0 and 7.4 with the products hth®  pH MINUS MICRO-BALLS
• Then perform a shock chlorination treatment with hth®  SHOCK^® Powder (wait between 24 and 48 hours before using the pool)

Insufficient amount of disinfectant

• Adjust the pH to 7.0
• Perform a shock chlorination treatment with hth®  SHOCK^® Powder if your pool is treated with chlorine or hth® BROME ACTIVATOR if your pool is treated with Bromine (wait 24 to 48 hours before using the pool)
• Use the flocculating cartridge hth®  REGULARFLOC (in the skimmer) if you use a sand filter
• Rinse the filter, leave the filtration running continuously for 24 to 48 hours

Insufficient filtration

• Increase the filtration time: Filtration time per day = T° of water /2 + 1h (example if 24°: 24/2+1 = 13 hours)

          > For more information on the optimal filtration time: see our tips

• Use the flocculating cartridge hth®  REGULARFLOC (in the skimmer) if your pool is equipped with a sand filter

Presence of limescale (hard water)

• Keep the pH between 7.0 and a maximum of 7.2
• Then use the flocculating cartridge hth®  REGULARFLOC (in the skimmer) if your pool is equipped with a sand filter

Sur-stabilisation

• Ask a pool specialist to check the stabiliser content (there must be less than 75 mg/l)
• If the stabiliser level is greater than this standard, you will need to partially or completely drain the pool
• After refilling the pool adjust the pH to between 7.0 and 7.4
• Then change the type of treatment by using the product hth®  STICK that contains unstabilised chlorine, also known as calcium hypochlorite (when there is no other product in the skimmer)

> To learn more about over-stabilisation: consult our specialist page.