Algae Type

What It Looks Like

Helpful Information

Green Algae

This is the most form of algae that we deal with in swimming pools. Green algae can be free floating in the water or can be wall-clinging. Green algae has the ability to clog pool filters and cause surface damage if left untreated. This algae can be treated fairly simply and quickly with aggressive shocking & algicide.

Yellow Algae

This is the MOST misdiagnosed form of algae. Yellow algae is a chlorine-resistant form of green algae. It often resembles dirt or sand on the bottom or sides of the pool. When trying to distinguish between yellow algae or dirt, follow this common sense rule of thumb: if it feels gritty it’s dirt; if it feels slimy it’s yellow algae. Yellow algae can be brushed away very easily, but returns quickly to the same location. It can survive in high levels of chlorine.

Black Algae

Black algae forms in cracks and crevices on the pool surface. We normally find black algae growing in, but not limited to, shady areas of the swimming pool. It is known creating a heavy slime layer and “skeletal growths” that make it impervious to normal chlorine levels.

Pink Algae

“Pink” algae or slime may be pinkish in color, but it’s not algae. The problem is actually bacterial in nature. The best algaecides to use for this problem are either Polymer Algicides or Silver Algicides. This type of problem can recur, if the conditions and water chemistry are hospitable.

Blue-Green Algae

This is another common algae found in swimming pools. As soon as the pool sanitizer level drops too low and the water conditions are right, this type of algae is likely to start blooming. This algae responds very well to shock treatment. The cloudiness that can result, after the shock treatment, is the dead algae.

Brown Algae

Brown algae are the largest of the algae: well-known forms include the giant kelp and the free floating sargassum weed. This algae seems to appear in your swimming pool after the closing stage, due to severely cold weather conditions.