Identify pool algae by type and select the correct chlorine-based remediation protocol

Steps

1. Visually identify the algae type: green algae (common, free-floating or on surfaces, cloudy green water), mustard/yellow algae (localized, often on shaded walls, chlorine-resistant, brushes off but returns quickly), or black algae (spotty, cyanobacteria with a protective outer layer, usually in cracks/rough plaster).
2. For green algae, brush affected surfaces, balance water, and shock with chlorine to a level sufficient to overwhelm the bloom, then run filtration continuously until water clears.
3. For mustard/yellow algae, brush vigorously (it resists chlorine more than green algae), shock at a higher dose, and treat all pool toys/equipment that contacted the water since it can survive off surfaces.
4. For black algae, physically break the protective outer layer with vigorous brushing before or during chlorine treatment, since chlorine alone often cannot penetrate an undisturbed colony, and expect to repeat treatment.
5. If using a copper-based algaecide as a supplement, follow label dosing exactly and check pH/water balance first, since copper products are more prone to causing staining when misapplied.