5 Steps to Kill Mustard Algae in Your Pool

Brush every surface thoroughly Mustard algae forms a protective film on walls, steps, and under ladders. Scrubbing breaks that film so chlorine can reach the algae.

Double the normal shock level Routine shocking won’t cut it. Raise chlorine to double the normal shock level and maintain it for a full 24 hours.

Use a mustard algae-specific algaecide Standard algaecides are often ineffective. A product designed for mustard algae gives you a better chance of wiping it out.

Clean or backwash your filter A dirty filter recirculates algae back into the pool. Make sure your filter is running clean to trap what you kill.

Test and treat for phosphates Phosphates feed algae and make chlorine less effective. If the problem keeps returning, remove phosphates or you will keep losing the battle.