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Help! My Pool is Yellow

Mustard Algae, also known as Yellow Algae, is a form of Green Algae that is highly resistant to Chlorine. Mustard Algae is yellowish green in colour and is often mistaken for dirt or sand on the bottom or sides of the pool and normally grows in shady areas. Because it is highly resistant to Chlorine, it needs addressing in a different way to Green Algae.

Common prevention techniques for Algae include;

  • Maintaining a Chlorine level of 2 – 4 ppm
  • Brushing at least once a week to keep it clean
  • Run your Filter for at least 8 hours in a 24-hour period.
  • Reduce the amount of Phosphates
  • Temperature below 80 degrees

To kill the Algae, you need to ‘Shock’ treat the Pool using Liquid Chlorine (Sodium Hypochlorite).

What to do

Check and address chemical levels before adding Liquid Chlorine.

Backwash and Rinse the system to enable the system to work at its optimum.

Check the Chlorine level. If the Chlorine level is low, add Stabilised Chlorine Granules dissolved in warm water.

Add Liquid Chlorine to the Pool. This needs to be added little and often. Dependant on the pool size, add 5 Litres of Liquid Chlorine directly where the Mustard Algae is. Repeat this process every week for 6-8 weeks. This is best done at the end of the day when there is less sunlight, so the Chlorine has longer to work before UV Rays start burning it off.

Please remember never swim directly after adding Liquid Chlorine. If you wish to swim in between the process, you must check your Chlorine level is ok before doing so.