Water doesn’t have to be dead to be safe. Natural swimming pools work with nature to
maintain a healthy swimming area, while forming a green oasis in the yard.
James Robyn likes to show people a photo of a natural swimming pool next to a conventional chlorine model. It was built in Germany for customers who couldn’t decide which they wanted. The difference is striking. The natural pool is a green-hued swimming hole bordered by a water garden, a stark contrast to the conventional model’s blue sterility. “We call the chlorine pool the Windex pool,” he says. (See photo right).
Robyn is president and CEO of Hackettstown, N.J.–based BioNova USA, one of the few American companies that design and build natural swimming pools, or NSPs. His point is that rather than the familiar disinfected vessel—infused with chlorine in an attempt “to kill everything but the bather”—the NSP is just what its name says: a natural body of water. That’s a big draw for some people; and it’s also what makes some people wary.
How It Works
Instead of relying on chlorine to kill germs, the NSP is a chemical-free, self-contained ecosystem. A pump circulates water between a deep swimming area and a shallow filtration, or regeneration, zone—the latter a miniature constructed wetland.
In the regeneration zone, hydronic plants embedded in gravel and other aggregates encourage the growth of microorganisms that remove pollutants from the water (see “Plants and Bacteria,” page 27). The moving water also passes through a skimmer that removes large surface debris (like leaves) and a biofilter that captures smaller ones (like bugs and hair).
The NSP is a totally closed system built over a watertight pond liner. Because it’s a closed system, the underlying soil’s permeability has no impact on its ability to keep the water clean. It also means that one can be built practically anywhere.
While all NSPs work on the same general concept, they come in a seemingly infinite range of shapes, with a variety of plants and rocks, and can include special features such as streams and waterfalls—which are often part of the pool’s operating system.
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