Moss In The Pool

By Mike Hahm

In 2009, a proposal crossed my desk that couldn’t be passed up. With cost savings, a reduction of the environmental impact and an innovative transformation in the way the city of Saint Paul, Minn., managed its pool’s filtration system, the proposal for implementing an industry-transforming moss-conditioning technology was a no-brainer.


The Pitch
Creative Water Solutions, a Minnesota-based company led by Dr. David Knighton, approached parks and recreation department officials with a new way for municipal pools to manage chemical usage and water filtration.

The pitch was unique, but straightforward: install a system comprised of Sphagnum Moss species to naturally condition the pool water, thus reducing the need for expensive and non-environmentally friendly chemicals.

The system had been used at residential pools and spas across the country for several years, but was never tested by the high bather-load and turnover rates that municipal pools deal with on a daily basis.

Internally, the possible drawbacks of piloting the technology were discussed, including the fact that the moss system doesn’t completely eliminate chemical usage.

However, if the system failed, pools could remain open by returning chemical levels to previous normal ranges. As far as officials could determine, there were no other major drawbacks.

What A Difference
After demonstrating the technology for various officials, including Mayor Chris Coleman, the outdoor Highland Park Aquatic facility, boasting several different amenities and a bather-load above 300, piloted the technology. Following the system’s installation, results were immediately measurable--from pH and chemical-level testing to water quality and clarity.

Additional daily monitoring revealed:

  • Chlorine use was cut in half by mid-summer and further reduced by the end of summer. Cyanuric acid was discontinued. Bicarbonate and acid use also fell to half the levels of 2008.

  • Prior to using the moss, the play features in the kids’ pool were faded, and some were almost white, even with lifeguards cleaning pool water lines and the features weekly. By the end of the pilot project, the colors were restored naturally, and looked like new--and the lifeguards stopped cleaning the water line.

  • At the beginning of the season, the surge tank for the Olympic pool was coated with slime, smelled, and was growing cottonwood trees; by the end of the summer, the surge tank no longer had the foul odor, the water was crystal clear, and the walls and floors were completely free of slime.

  • When the pools were drained for the winter, they required no cleaning at all. In fact, they appeared as if they had been power-washed with strong acid.

  • Users commented that they no longer smelled like chlorine, and their hair was not discolored.

  • The immediate success of the pilot project led to the installation of the moss-filtration system at the city’s indoor Great River Water Park with similar results.

  • Not only have city officials embraced this technology throughout the aquatic facilities, but they’ve challenged partner and neighboring agencies to do the same.

The cost benefits and positive environmental impact have been quickly apparent, but as resources diminish and demand for parks and recreation services continue to grow across the nation, the industry needs to embrace innovative technologies that offer higher-quality services at a better value to residents.

Mike Hahm, CPRP is the director for the parks and recreation department in Saint Paul, Minn. For more information, visit

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First-year savings compared to previous year for pilot project:
Total--More than $100,000 increase in revenue
Chemical savings--$36,000
Maintenance staff savings--$40,000
Increased revenue from marketing advantage--$30,000