How to Get Algae to Stop Coming Back in a Pool

Algae is a stubborn and unwelcome visitor to your pool or spa that can sometimes be difficult to keep from returning. A simple-structured plant, algae can attach itself to the side of the pool and still be present even when it appears to be eradicated. In certain weather conditions it can rebloom easily, adding to the difficulty in getting rid of it. The proper cleaning steps, the right chemical mix and specific agents designed to kill stubborn algae can help you eliminate it permanently from your pool.

• 1

  Test your pool water for the proper chemicals and pH level. Balance the water as you normally would to reach the proper pH level before beginning your algae removal regimen.

• 2

  Check your filtration system -- a system that is not working properly can be a culprit in returning algae blooms. Make sure there is good flow to the entire pool. Turn on any automatic cleaners you have for your pool and expect to run your filter 24 hours a day until the algae is gone.

• 3

  Shock the pool for green or black algae by super-chlorinating it. This means adding a shock treatment until the chlorine levels are between 5 and 10 parts per million (ppm). For yellow algae, skip the shock treatment and continue to Step 4.

• 4

  Scrub down the sides and bottom of the pool while the pool is being shocked. Push everything toward the main drain as you use the scrubbing tool on the vacuum head. Backwash as necessary to maintain pressure if the filtration system becomes sluggish.

• 5

  Add algaecide to the pool. If you have shocked the pool for green or black algae, be sure the chlorine level has returned to below 5 ppm. For green algae, a standard algaecide works best. For black or yellow algae, a copper algaecide must be used. Follow the manufacturer's instructions, since copper algaecide can stain plaster pools.

• 6

  Brush and vacuum the pool again. Backwash the filter if necessary.

• 7

  Rebalance the pool water levels. Check them regularly. Do not allow the pH level to become too high or the chlorine level to get low, as these are the perfect conditions for algae to grow.

• 8

  Brush and vacuum the pool daily until you are certain the algae is not returning. Algae attaches itself to the pool with a root system. Chlorinating kills the top layer of the organism, but the roots will remain unless the algae is ripped away from the pool surface and the entire plant is exposed to the chlorine.

• 9

  Rub stubborn spots on tile or plaster pools with a trichlor tablet or stick, wearing protective gloves to keep the tablet from touching your skin. The abrasive action of rubbing the chlorine directly against the algae spot will both tear the plant away from the surface and kill it in the process. This is a good spot-cleaning method when necessary.

• 10

  Deter further algae blooms by maintaining the filtration system and keeping the filter clean. Maintain proper levels of pH and chlorine, especially in hot weather.