Algae may appear in UV lamps system treated swimming pools



When the water is hot, algae may appear in UV lamps system


When the water is hot (the temperature is higher than 28°C), algae may appear in UV lamps system and liquid active oxygen (hydrogen peroxide) treated swimming pools as an ongoing treatment.

This is simply due to:

  • Faster evaporation of active oxygen, linked to the water temperature
  • Scale deposits: the hotter the water is, the more lime deposits will build up, enabling the algae to fasten on

To destroy the algae, you need to carry out the following treatment:

  • Switch off the UV lamps
  • Set the pH at 6.8 - 7.0
  • Acti HP granule (a non-stabilised chlorine treatment: 150g/10m3)
  • Add Acti Anti-Calcaire anti-scaling agent (1l/20m3)
  • Rub off the marks
  • 24 hours later, switch the UV lamps back on
  • Raise the pH and balance the water if need be

That way, any algae that resist the active oxygen will be destroyed.

Once the UV lamps are in operation, they will destroy the excess unstabilised chlorine used for destroying algae.

To prevent the return of this problem:

  • Remove scale from the filter: ACTI Nettoyant Filtre filter cleaner; 1l/75kg of filter mass if using a sand or glass filter
  • Balance the water (use the Actisoft software for the right doses of products)
  • Add ACTI Meltalfix: 1kg/50m3 (in order to avoid the active oxygen being pointlessly consumed by reacting with the metals)
  • Add ACTI Anti-Calcaire: 1l/20m3 (to avoid the build-up of scale deposits on the walls, thereby enabling the algae to fasten on)

NB: If the water temperature is higher than 30°C, this problem may reoccur periodically, because the algae will develop faster than they are destroyed by the active oxygen and their passing under the UV lamps. In that case, you then have to make provision for one to two treatments of Acti HP granule (unstabilised chlorine) every month, depending on the swimming pool’s needs (to deal with its level of use, external pollution), in order to destroy the algae.

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