Keep chlorine high and brush weekly.

Yes, but you need to stay on top of it.

Mustard algae (yellow algae) is tougher than green algae. A normal shock won’t kill it — it usually just goes dormant and comes back when you relax. The trick is to raise your chlorine to shock level (check your pool’s CYA levels) and hold it there for 48 hours. Brush every surface — walls, floor, steps — at least once a day during that time. The algae hides in crevices and needs physical disruption.

After that, don’t drop back to a minimum chlorine level. Keep it around 3–5 ppm (depending on your stabilizer) and brush weekly. Also clean or backwash your filter more often — dead algae can hide there and reinfect the water.

If it keeps coming back, you might have a phosphate or nitrate problem. A phosphate remover can help, but the high chlorine + brushing routine works for most people.

This algae doesn’t give up easily. Neither should you.