The pool and spa industry has never been completely comfortable with halogen sanitizers. This merely reflects the general attitude of its customers, who find some aspects of chlorine and bromine use troubling, but have broadly accepted their necessity.

This vague but persistent disquiet has launched a number of innovations over the years that help produce clean, clear water with a reduced level of chlorine, all purporting to provide a more natural experience.

In this category one could include UV, ozone and minerals, among others. Recently, a plant-based product that uses the proven water conditioning properties of sphagnum moss has entered the market. It is growing in popularity and making true believers of industry veterans who have seen a great many such products come and go. "I've been doing this since 1968 and I've never seen anything like it," says Gary Grimes, president, Main Line Commercial Pool and Spa, King Of Prussia, Pa.

Grimes takes care of mostly commercial pools in the Philadelphia area. He says he thought sphagnum moss sounded like "snake oil" until he tried it and his customers started telling him what they were seeing: a dramatic lowering of chlorine usage, and an even more impressive lowering of chloramine production.

He began using sphagnum moss about a year ago and has been impressed with its performance in pool after pool (including his own), which he has documented. Currently, Main Line is using the moss in 15 to 20 commercial pools with plans to install it soon in five new locations.

An example typical of his experience has been the Spring Valley YMCA in Royersford, Pa., where Grimes began using the moss in three different bodies of water.

"Before we installed the moss," he says, "they were backwashing the family pool three times a week, they were draining the spa every Sunday night and backwashing the activity pool once a week. And they had tremendous chloramine issues.

"After we installed the moss, the chloramine issue has gone away entirely, and they're now backwashing the family pool once a week, dumping the 3800-gallon spa once every three weeks and the backwashing activity pool once a month. They wrote a paper on their savings, which have been huge."

Grimes says the pool had been running around 3 to 5 ppm chlorine before the moss was added, "and if it got any lower, they'd start to get cloudiness. Now they're doing 1.4 ppm."

An important effect of the reduction in chlorine usage is a dramatic reduction in chloramines (by-products of the chlorine reaction with pool waste. When chloramines become airborne around pools they irritate lung tissues and have been shown to contribute to asthmatic reactions.)

"The first pool where we did this was the competition pool at The Kroc Center in North Philadelphia. It's about 380,000 gallons or so. The swim coach there is a guy named Jim Ellis. (They actually made a movie about him a few years ago called 'Pride,' which received some acclaim.)

"But anyway, in talking to him, one of the major issues that he has with kids from the inner city is asthma. Since we put the moss on, his claim to me is that somewhere between 90 to 95 percent of all the asthma attacks during practice have gone away.

"That's one thing you especially notice is on indoor pools with the moss — the dramatic effect on the chloramines."

Hot Tubs, Too

Paula Landry, co-founder of Mario's Pool & Spa, in New Brunswick, Canada, is more interested in the benefits for spas than commercial pools. Her company has been using Spa Naturally (the trade name for Creative Water Solutions' (CWS) sphagnum moss product for spas) for three years and she says that 90 percent of her customers are on the system.

"You still need to use some sanitizer, but it's greatly reduced. It has no smell, no visible particles and the water stays clear. Because we use less bromine, which has a high pH, the product in effect helps keep the pH down.

"And we've found that water lasts longer. You might only have to change your spa water two times each year instead of four or even six times. It's more forgiving because the moss doesn't allow algae to grow, even if you've left it alone for a couple of weeks."

Landry says it's important to start with a biofilm-free spa before starting the moss regimen, so she makes sure the biofilm has been flushed out of the plumbing — even on a brand new spa. And she admits, this takes some work, "but once you get the plumbing clean and start using the moss, you'll find that you have very little or no problem with algae. Because bacteria doesn't have a place to grow, you use very little sanitizer."

"My husband is allergic to bromine, even at moderate levels, so we gave the product a try. It worked beautifully and now he's able to enjoy the hot tub because of the reduced sanitizer level."

A Short Bio On Biofilm

In terms of operation, this sanitizing aid works very simply; it's just moss in a tea bag. Water flows through the mesh, contacts the moss, and flows back into the pool or spa. In this process, the water loses its ability to support biofilm — the main training base and safe haven for bad actors such as algae and bacteria in the pool environment.

That is the kernel of the argument. Sphagnum moss prevents the formation of biofilm, and that seems to leave algae and bacteria with fewer places to hide from chlorine and bromine. Nobody seems to know exactly why exposure to this particular type of moss has this particular effect. So far, the science behind the product is mostly empirical — more about the what than the why.

Research published by CWS can be summarized as follows:

Whenever bacteria, water and a surface are combined in any vessel, bacteria migrate to the surface and set up housekeeping. These biofilm colonies are complex in design. The first bacteria that adhere to the surface produce and secrete a sticky matrix of complex sugar molecules that also incorporate proteins, nucleic acids and other compounds from the immediate environment.

Little known by the pool and spa industry until now, the biofilm matrix absorbs chlorine, bromine and other reactive ions into the sticky molecular matrix that covers the living bacteria. The ions may kill the bacteria closest to the surface, but billions of bacteria remain unharmed in the depths of the biofilm. These bacteria also quickly divide to replace the ones killed by the chemicals.

The problem then is that conventional sanitizing chemicals in pools and spa don't deeply penetrate the biofilm, and therefore do not kill most of the bacteria contained within it.

By inhibiting the formation of biofilm, sphagnum moss denies these bacteria refuge.

Using Moss

An obvious potential market for sphagnum moss is indoor pools — as evidenced by Grimes' successful installations — and due to impressive results reported by CWS in test pools where the moss was installed:

After a recent 33-week study conducted at the indoor pool of a national fitness center chain, the company discovered that the moss significantly reduced the amounts of disinfection by-products (DBPs) in the water and volatile organic compounds (VOCs) in the air — thereby reducing odor, decreasing chemical smells and their unpleasant side effects on swimmers, lifeguards, maintenance and other staff.

"Our data shows that besides reducing the amount of chemicals needed to treat water (and lessening irritants to swimmers, maintenance time and corrosion of motors and liners) the moss is also providing measureable air quality benefits," says Vance Fiegel, chief scientific officer at CWS.

Some Assembly (May Be) Required

For such commercial pools as described above (those already equipped with surge tanks) no modification is required to prepare the system to use moss. A large pre-packaged mesh bag of the stuff is simply lowered into the tank. The circulation of the pool is all that is needed to treat the water, and the moss is changed on a monthly cycle.

For commercial pools without a surge tank and for all residential pools, a contact chamber must be plumbed in. In this case, the contact chamber is installed off-line, so that water flow through the chamber can be controlled.

In most residential spas, no contact chamber is required. The SpaNaturally SpaRefill can be placed directly in the filter bay or weir or other area of very active water flow.

In a sense, sphagnum moss is a very old product — it's just new to the pool and spa industry. Proponents believe it plays a crucial role in maintaining healthy water the natural ecosystems from which it comes.

"In actuality, the experience base for the sphagnum moss is much greater than one imagines. It has been clarifying water in northern lakes for millennia," Grimes says.

Time will tell if it can manage the same trick in today's man-made aquatic environments.

Comments or thoughts on this article? Please e-mail editors@aquamagazine.com.

Scott Webb is Executive Editor of AQUA Magazine.