You may have noticed that your pool water is no longer sparkling blue, or the walls seem to have a strange growth on them lately. This is most likely algae. There are several types of algae that grow, and each one requires a bit of a different method to remove. You will need to determine which variation, and then plan your method of attack to eliminate pool algae.
Green Algae:
This is the most common variety. Green algae is frequently found free floating in the water, although it also will cling to the walls. It can also appear as "spots" on surfaces, particularly rough areas, or places where circulation is low or as large surface sheets of green slime! To eliminate, shock the pool, heavily! Brush the walls and floor toward the main drain and once the chlorine level is below 5 ppm, add an Algaecide, brush again and vacuum the debris.
Yellow Algae:
Also referred to as mustard algae, this wall clinging algae can form in shady areas. It is sheet forming, and can be difficult completely eliminate. This variety is resistant to normal chlorine levels and re-infection is common. To eliminate pool algae of this kind, shock the pool to 30 ppm chlorine, brush and vacuum debris, add algaecide and brush again. Then vacuum debris and backwash filter. Steel brushes are recommended for plaster, and nylon brushes for vinyl pools. It is best to run your filter 24 hours a day while battling this algae.
Black Algae:
Difficult to eliminate due to the strong roots and protective layers over top of the black algae plant. Black algae will appear as dark black or blue/green spots, usually the size of a pencil eraser tip. Brushing is essential here, and once knocked off, vacuum and backwash filter immediately! Of course, you must follow the above steps as well; shock the pool, brush and vacuum, add algaecide.
