Black algae can turn a clean pool into a never-ending battle, and the worst part is you might be spreading it yourself without realizing it. We dig into what “black algae” really is (often cyanobacteria), why it clings so stubbornly to plaster, and why the usual quick shock routine often fails unless you do the one step most people skip: aggressive brushing to break the protective heads so chemicals can reach what’s underneath. We also get specific about transmission and cross contamination....

Show Notes

Black algae can turn a clean pool into a never-ending battle, and the worst part is you might be spreading it yourself without realizing it. We dig into what “black algae” really is (often cyanobacteria), why it clings so stubbornly to plaster, and why the usual quick shock routine often fails unless you do the one step most people skip: aggressive brushing to break the protective heads so chemicals can reach what’s underneath.

We also get specific about transmission and cross contamination. Spores can hitch a ride on anything wet, from a bathing suit that went from the ocean to the pool, to the damp tools riding in the back of a service truck. We talk through the biggest culprits, including nets, leaf rakes, bags, and especially stainless steel brushes, plus how low free chlorine levels make the next pool far more likely to “catch” black algae after exposure.

Then we lay out a practical pool maintenance plan for black algae treatment and prevention: how to approach superchlorination safely, when topical products like granular trichlor or broken cal-hypo tablets can help, and how copper options (including chelated systems like PoolRx) fit into longer-term control without creating staining issues. If you want fewer callbacks, fewer route-wide outbreaks, and a clear plan for stopping black algae from coming back when chlorine dips, this one is for you. Subscribe for more pool service training, share this with a tech who needs it, and leave a review with your toughest black algae question.

We break down why black algae is so hard to kill, why it often comes back, and why it is more like cyanobacteria than typical pool algae. We also explain how black algae can spread from pool to pool through damp tools and low chlorine, plus the practical steps we use to treat it and prevent cross contamination.
• What black algae is and why it resists normal shocking
• How spores can hitchhike on wet suits, towels, and pool tools
• Why brushing the heads off is nonnegotiable for treatment
• When superchlorination works and why circulation matters
• Granular trichlor and cal-hypo tablet options for topical killing
• Copper approaches like PoolRx and dosing cautions to avoid staining
• Dedicated nets, rakes, and stainless brushes to stop route-wide spread
• The “never let chlorine hit zero” rule after a black algae cleanup
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