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How to Clean Green Algae From a Swimming Pool

By Dale Devries
Clean Green Algae From a Swimming Pool

Green algae in a swimming pool can be hard to get rid of. If the weather has been particularly hot and humid it strips the pool of chlorine and allows algae and bacteria to grow. The green growth on the sides and bottom of the pool is a common problem among pool owners. You can get rid of it but it will take some time and constant work. The biggest inconvenience of the algae and the cure is that you cannot go into the pool while the chemicals are working to clean it.

Brush off the walls and floor of the pool and remove as much of the algae as possible. This will decrease the time it takes to get rid of the algae.

Fill a large bucket with water and add 1 lb. of chlorine shock for every 7500 gallons of water in your pool. Add the chemical to the water. You may want to wear a mask when adding the shock to the water as it can be very strong. Dissolve the shock in the water and pour into the pool.

Keep your filter system running continually and backwash when you see the pressure start to go down. You may have to backwash several times before the water starts to clear.

If you aren't seeing significant improvement within 24 hours, you will need to add another dose of shock. Use the same concentration and keep the filter system running.

When the algae dies it will look a gray or white color. When you see this start to vacuum it out of the pool. You may have to clean out your filter system a couple of times while you are vacuuming. Once the algae is gone, you will have to allow the chlorine level to come back down to a safe level for swimming before you allow anyone in the pool.


Things You Will Need

  • Chlorine Shock
  • Bucket
  • Water hose
  • Long handled pool brush


  • Once the pool is back to normal, clean your filter system really well or change out the sand. Algae will come back quickly if the chlorine level goes down for only a short time.


  • Use caution while using chlorine shock. It can cause breathing problems and cause skin irritation and burns.