Black algae product test results surprise

Algaecide trial successfully treats black algae in a Florida commercial swimming pool with over 14 years of documented infestations.

BENTONVILLE, Ark. – Rudy Stankowitz has a mission. He wants to help pool operators defeat black algae – and he may have found a way to do it. Stankowitz recently ran a real-world experiment to see whether prolonged contact with low levels of copper would kill black algae. The results were surprising.

In less than a month, Stankowitz and his team were able to reduce severe black algae in a Florida commercial pool by over 50%. The facility had struggled to control black algae for over 14 years. Stankowitz deemed the trial a success and concluded that ongoing treatment would continue to reduce the infestation.

Stankowitz knew beforehand that copper could kill black algae, but there was a problem. The level normally required for a lethal dose would far exceed EPA safety guidelines. Then he found a perfect opportunity to test his hunch that a lower level would kill black algae over time.

“As luck would have it,” Stankowitz said, “my colleague Doug McKenzie from Earth Science Laboratories had reached out to talk about my article ‘The Black Algae myth.’ This was about the time we had identified and secured a swimming pool with colonization for testing. Doug offered to supply us with an algaecide in a quantity sufficient to treat our 230-gallon pool.”

McKenzie is the Business Manager for ESL’s Recreational Water division. The algaecide he supplied for Stankowitz’s trial is called AlgaeShield®. ESL designed it to kill algae for up to 30 days with a single dose. When Stankowitz and his team applied it to their test pool, they saw an unexpected result.

“A wave of blue washed quickly throughout the pool,” Stankowitz said, “much faster than I have witnessed in other copper tests. By the time the brushing of the pool was complete, the water in the pool had developed a turbid blue haze. This was well beyond the normal ‘bluing’ experiences that we were anticipating.”

Stankowitz speculated that a “spreading agent” had helped the algaecide to disperse so quickly. But McKenzie said that the product contains no such agent. “The beauty of our chemistry is that it disperses quickly and evenly throughout an entire pool without additives. Better dispersion equals better performance. That’s what Randy observed in his trial.”

A full report of the trial is available at

A video demonstrating the dispersion of AlgaeShield can be viewed at

Earth Science Laboratories Inc. creates innovative water treatment products for commercial, municipal and agricultural use. These include AlgaeShield and the popular PristineBlue® system for residential pools, spas, and hot tubs. AlgaeShield and PristineBlue are EPA registered and NSF Certified to ANSI Standard 60. More information is available at