4 Things to Know About Mustard Algae in Pools

Mustard algae looks like yellow-green dust on pool walls and floors It brushes off easily but returns within hours, unlike green algae which floats and clouds the water.

Normal chlorine levels won’t kill mustard algae It requires 2 to 3 times the usual shock dose to reach breakpoint and actually eliminate it.

The treatment demands daily brushing for at least a week Brush every surface including walls, floor, ladder, and steps, and run the filter 24/7.

If it returns after the first shock, use a mustard-specific algaecide Apply the algaecide and repeat the shock treatment — this is a war of attrition, not a quick cleanup.