The Free Press, Mankato, MN

Local News

May 27, 2010

Moss in the pool can be a good thing

Use of moss as filter is catching on

MANKATO — On a recent reconnaissance trip to a pool in St. Paul, the Mankato YMCA’s John Kind did something you don’t often see CEOs do.

“I actually bent down and scooped some of the water into my mouth,” Kind said of his pool visit. “It tasted like tap water.”

In other words, that pool water, filtered by sphagnum moss from New Zealand, danced across his palate a little differently than the water from his own facility’s pool.

But come Saturday, visitors to the YMCA pool will be in for a refreshing surprise: The chlorine smell, taste and feel that has long dominated aquatic life at the Mankato Y should be gone, replaced by a new moss-filtered version of it.

The pools will close at noon today. When they reopen Saturday, the water will have passed through the latest, and perhaps cleanest, form of pool water treatment.

Sphagnum moss, a filtration experiment attempted first — and with stunning results — in St. Paul, has come to Mankato. The local Y is the first  in the country to trade in a chlorine-based system for one that will, staff hopes, leave swimmers’ skin feeling better, pool surfaces feeling less scummy and slimy, everyone’s noses happier, and blond hair less green.

The idea came from Y member and community booster Leigh Pomeroy. He’d mentioned to Kind that moss had proven to be a better and cleaner way to filter pool water. Kind looked into it and became intrigued.

He talked to the people at Recreation Aquatic Solutions, and they offered to give a Mankato Y contingent a tour of pools in St. Paul that have switched to moss.

The tour took place in March. And upon entering the pool area, the difference, they say, was staggering.

“Immediately there was not that chlorine smell,” said Laura Diaz, program director. “You could take deep breaths and it was fine. And the water was blue.”

Sphagnum moss, it seems, is one of nature’s most efficient cleaners of water.

In an article posted on, the company’s website, founder David Knighton explains how sphagnum moss, which grows naturally in Minnesota and other parts of the world, had been used for centuries by people to preserve food, heal wounds and keep drinking water fresh. Some American Indian tribes even used it to diaper their babies.

But as medical and preservation practices improved, the use of sphagnum virtually ceased. Until now.

Recreational Aquatic Solutions and other companies are engineering water filtration systems that are growing in popularity. And while there are more than 100 varieties of sphagnum moss, research has led these companies to focus on just a handful that are particularly efficient water cleaners.

Not only does the moss filter and kill bacteria, but it also breaks down biofilm (the slime that accumulates on surface of a pool or spa). Without that pesky biofilm around, a lot less sanitizer is needed in the body of water. Kind said he’s hoping to use as much as 80 percent less chlorine.

And after the Mankato Y installs its system, Kind said a group of CEOs from other Ys around the country plan a visit to Mankato to see the results.

“We’re trendsetters,” Kind joked.

While the lower levels of chlorine will mean lower chemical bills, the move to moss won’t necessarily mean a less expensive system. Initial costs to install the new filtration system totaled about $7,000, which Kind predicts they’ll recover in fewer than two years by not having to repair equipment or replace water as much. But it still costs money to replace the moss each month.

Diaz says the real benefit, however, will come from the satisfaction Y members get from a more refreshing pool experience.

“It’s good on the swimsuits, doesn’t fade them, there’s not that potential scuminess, sliminess that would be on your skin, you won’t need extra lotions or moisturizers. For swimmers with blond hair, there’ll be no more green hair,” she said. “You could be drinking the water.”

Diaz also realized that with a healthier pool experience, people with allergies or asthma — people who maybe were not able to use the pool before — can use the pool again.

“More people will be getting into swimming,” she said. “Swimming is a lifelong activity, and allowing people to get back into it is a great feature. It sets us apart.”

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