How To Eliminate Swimming Pool Algae

Algae in a swimming pool
  • 1-5 hours
  • Intermediate
  • 0-150

The most common form of swimming pool algae is green algae. Green algae will develop when your pool chemistry is below par. Sometimes lightning storms will encourage green algae. The lightning will reduce the level of chlorine in your pool and create nitrogen on which the algae feed.

Step 1 - Remove Excess Algae

Although the algae in swimming pools may seem attached to the walls and floor of your pool it is actually free floating. Brushing over the walls and floor will remove a lot of the algae.

Step 2 - Check Chlorine Level

The pool algae have grown because the chlorine level in your pool has fallen. Also test the PH level of the pool and make sure it is within the range of 7.2 to 7.6 so chlorine you add will be more effective.

Step 3 - Add Pool Shock

testing pool chemicals

Add a chlorine based swimming pool shock to the pool using the manufacturer’s recommended dosage rate for killing algae.

Step 4 - Run the Pool Filter System

Leave the pool filtration system running permanently until the algae problem has been cured.

Step 5 - Look for Signs of Dead Algae

As the algae are killed they form a whitish cloudiness in the water or may settle to the bottom.

Step 6 - A Second Dose?

If there are still large traces of green in the pool after 24 hours, repeat the shock treatment.

Step 7 - Vacuum the Pool

Once there is no green color in the pool use the pool vacuum to remove all dead algae sending them to waste, not the filter.

Step 8 - Clean the Filters

man checking pool filter

Clean or backwash the pool filters to clear out the dead algae. Failing to clean the filter will encourage the return of the algae.

Step 9 - Check Chemical Condition of Pool

After cleaning the filters test the pool for chlorine content, PH level, alkalinity and calcium hardness and bring them to within ideal levels.

Step 10 - Filtration

Return the filtration to normal operation times, not 24 hours a day.

Prevention of algae blooms is better than having to cure them so check your pool every day and pay particular attention to the PH level. When the PH level falls, the chlorine in the pool is less effective and the algae will start to grow. You should see early signs of algae growth as small patches of green. This should prompt you to test the water.