How to Get Rid of Pool Algae (and Keep It from Coming Back)
Green, yellow, or black — here's how to identify the algae in your pool, clear it fast, and stop it from returning in Houston's heat.
Algae blooms are the most common call we get during a Bay Area summer. Warm water, high sun, and the occasional tropical downpour create perfect conditions — and a pool can go from sparkling to green in under 48 hours if chemistry slips.
Start by identifying what you're dealing with. Green algae floats and clouds the water; it's the easiest to treat. Yellow (mustard) algae clings to shaded walls and resists normal chlorine levels. Black algae roots into plaster and requires brushing with a stainless steel brush to break its protective layer.
Before you shock, test and balance. Bring pH down to 7.2 and confirm your cyanuric acid (CYA) isn't above 50 ppm — high CYA neutralizes chlorine and is the #1 reason shock treatments fail in Houston pools. If CYA is high, partially drain and refill before treating.
Shock with calcium hypochlorite at roughly 2 lbs per 10,000 gallons for green algae, double for mustard, triple for black. Run the pump 24 hours. Brush every surface — walls, steps, behind ladders, under the skimmer lip. Algae hides where water moves slowest.
Clean or backwash the filter once the water clears. Dead algae clogs media fast, and a dirty filter will recycle the bloom right back into your pool. For DE and cartridge filters, a full breakdown clean is worth the hour.
Prevention is cheaper than recovery. Hold free chlorine at 3 ppm, keep CYA between 30 and 50, brush weekly, and run the pump at least 8 hours a day in summer. If the pool is already past saving, our green pool cleanup service clears most blooms in three to five days, including across Friendswood — and a weekly route afterward keeps chemistry locked in.