Due to algae's microscopic size, it takes literally millions of these plants to accumulate to be noticed by the naked eye! By that time it may be too late and very costly to correct. As we tell all our customers: This best way to eliminate algae is through prevention! (This is also why we are such proponents of salt water chlorine systems.)
The most common form of algae in swimming pools is "green" algae. Green algae (varies in color from blue-green to yellow-green to dark-green) can be free floating in the water (turning the water a hazy-green) or can be wall-clinging (patches of green). Green algae can be treated fairly simply with the right amount of brushing, shocking, and algaecide.
Treatment: Have water properly analyzed to ensure PH is at proper levels and balance the pool water. Pools treated with chlorine should be brushed thoroughly, then shocked, raising the chlorine levels above 30,000 ppm. Also, add a strong dose of Algaecide 60 to the water. Continue to check the pool's filtration throughout this process to ensure proper water flow. You may have to repeat this process a few times in order to eradicate entirely the algae.
"Black Algae" (actually blue-green algae) forms in cracks and crevices on pool surfaces, especially plaster finishes. We normally find black algae growing in, but not limited to, shady areas of the pool. Black algae is more typically found in concrete or plaster finished pools because of their rough surfaces. It is known for a heavy slime layer and "skeletal growths" that make it impervious to normal chlorine levels. Black algae usually doesn't have any effect on water clarity, it just makes your pool appear to have black spots on the surface.
Treatment: Have water properly analyzed and balanced. Prior to and during treatment, the algae MUST be thoroughly brushed in order to "break open" the slime layer. Failure to do this critical step will prevent the treatment from working. Shock the pool very aggressively and continue to brush the black algae. Add substantial amounts of algaecide 60.
Mustard algae is a chlorine-resistant form of green algae (yellow-green to brown in color). It often resembles dirt or sand on the bottom or sides of a pool.
Treatment: Same as black algae.
In certain cases, when a pool is full of algae, the algae must be vacuumed directly out of the pool. This can be accomplished by brushing the algae off the walls, then adding a ‘floc' to the water, which coagulates the algae and causes it to settle. Once it settles, it should vacuumed directly out of the pool. When attempting to floc a pool, follow the directions on the bottle very carefully.
Well hopefully you will not be burdened with algae in your swimming pool this year. As I mentioned earlier in the article, salt chlorine generators are the best way to prevent algae in your pool. This is because they produce a consistent feed of natural chlorine going into your pool all the time, which will also allow you as a pool owner to be gone for a few days without being too vigilant of your pool, but still coming back to a crystal clear, algae free body of water. I'm always amazed at how many pool owners think that algae a standard part of swimming pool ownership. This clearly does not have to be the case, as we have many customers at River Pools who have never even seen algae in their swimming pool. Of course, this is also why just about every one of our customers uses a salt chlorinator.
Good luck and happy swimming!