Yellow Algae

Yellow (Mustard) algae is usually found on the shady side of the pool in “sheets”. I’ve also seen it start many times in the spa, and then spread to the pool. This type of algae has frustrated many homeowners through its propensity to go away, come back, go away, etc. Again, strong shocking, brushing, and filtration is the fix. A preventative algaecide will help keep it from coming back, as will extended filtration cycles. If possible, keep birds, dogs, and other wildlife out of the pool, as this is a common means of diminishing your chlorine level. I also believe it isn’t a good idea to wear a swimsuit in the lake and then use it in the pool – there are too many “things” in the lake that make pool maintenance harder.

Products specifically designed for mustard algae do a good job removing it, but they don’t seem to work very well at keeping it away. Regular brushing, shocking, and longer filtration runs are the best ways to keep it from coming back.