Getting Rid of Swimming Pool Algae

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Andrea and Paulette go long on algae—the real science, the field diagnostics, and the no-nonsense remediation that actually works on a Tuesday in August when the phone won’t stop ringing. Pulling from training content and field notes, they break down how to tell algae from look-alikes (metals, pollen, fine dust), why water balance and sanitizer demand dictate outcomes, and how to choose the right kill-sequence for mustard/yellow, black (cyanobacteria biofilm), green blooms, and stubborn pink slime/white water mold co-contaminations.

They also reference Rudy Stankowitz’s book, How to Get Rid of Swimming Pool Algae (Amazon), for deeper reading on species behavior, biofilms, and step-by-step playbooks that complement today’s talk.

Chapter Markers / Timestamps

0:00 – Cold open: “Is it algae… or just copper?”
 2:12 – Why algae wins when demand beats delivery (sanitizer kinetics 101)
 6:45 – Field ID: green, mustard/yellow, black (cyanobacteria), and the “not algae” suspects
 12:10 – Water balance triad: pH, TA, and CYA’s impact on free chlorine efficacy
17:38 – Brushing matters: mechanical disruption vs. biofilm defenses
22:30 – The mustard/yellow protocol (when and how to go higher on FC)
27:55 – Black “algae” = cyanobacteria: surface penetration, heads vs. roots, patience game
33:20 – Filters as crime scenes: clearing, backwashing, and when to deep clean
38:05 – Phosphates: food vs. famine—when removal helps and when it’s a red herring
43:00 – Borates as drift control and slime deterrent (what they can and can’t do)
47:18 – AOP/UV/ozone: supplemental oxidation for heavy bather loads
52:40 – Look-alikes roundup: metals, pollen, plaster dust, and “dead algae” myths
57:15 – Off-season & startup traps: winterized pools, spring turn-ups, and biofilm seeding
1:02:10 – Rapid-response checklist you can hand to a tech

Key Takeaways

• Identify before you treat. Color + texture + location + “does it brush off?” beats guessing.
• Sanitizer effectiveness is conditional. As CYA rises, the % of active hypochlorous acid drops; dose and contact time must adjust.
• Mechanical + chemical wins. Aggressive brushing and good circulation expose biofilms so oxidizers can work.
• Mustard/yellow needs elevated FC (and whole-pool exposure for toys, nets, lights, covers).
• Black “algae” is cyanobacteria anchored in porous surfaces; expect repeated disruption and sustained levels—not a one-and-done.
• Filters tell the truth. Restore flow, deep-clean media, and fix bypass/broken laterals or you’ll chase the same bloom.
• Phosphate control is situational. It can lower regrowth pressure but doesn’t replace sanitizer.
• Borates steady pH and deter slime, but they’re not an algaecide.
• Document everything. Photos, readings, doses, and filter maintenance notes protect you and speed future calls.

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