Yellow Mustard Algae
Yellow or Mustard algae is the most common type of pool algae. It is most common in warm sunny areas, such as along the sunbelt from California to Florida. It’s identified by it’s color, which ranges from a very light yellow to a dark mustard green.
Mustard or Yellow Algae typically starts to grow when your sanitizer levels get too low or is being consumed too quickly to keep the algae at bay. This is common during the hot summer months when chlorine burns off more quickly in your pool.
Typically this algae starts growing in the shadiest areas of the pool along the walls. It is relatively easy to brush off.