1. Life & Culture

Pooling nature

This swimming pond in Massachusetts is the handiwork of BioNova Natural Pools, a company based in Germany.
This swimming pond in Massachusetts is the handiwork of BioNova Natural Pools, a company based in Germany.
Published Oct. 6, 2012


Walk out the front door of a house under construction in Santa Monica, Calif., and the bridge over a koi pond in the front yard leads to stepping-stones, then a meditation deck that appears to float in the water.

To the casual observer, the pond looks like pretty landscaping. But when construction is completed, it also will be the filtration system for a backyard swimming pool that will use plants, gravel and mechanical filters instead of chlorine or other chemicals to clean the water. It's called a natural swimming pool or swimming pond, and it's an idea that some in the industry believe will be the next big thing in health- and environment-conscious communities.

Chlorine has long been the industry standard to keep pool water clean and clear, but consumer demand for alternatives has prompted the emergence of new technologies, including the saltwater systems that came into vogue a few years ago and the copper-and-silver ionization and ozone-gas systems that are increasingly popular.

"I don't like the stuff that goes into swimming pools," said Philip Daughtry, a poet who often swims in the koi pond he refers to as his "backcountry swimming hole." Daughtry's swimming pond was constructed by Environmental Sculpturing in Topanga Canyon near Santa Monica. That outfit is also installing the Santa Monica pond being built in a Zen-influenced, minimalist style.

Natural swimming ponds take many shapes. Some look like traditional pools, and others take forms that more closely mimic nature.

Natural swimming ponds are relatively new to the United States, but more than 20,000 have been built globally, according to a spokesman for BioNova Natural Pools, a German company with North American headquarters in New Jersey and three natural swimming pools built or under construction on the East Coast. Next year BioNova will install what will be the first public natural swimming pool in the country at Webber Park in Minneapolis.

"A lot of people are interested in leading a chemical-free lifestyle. We're not using any devices, sterilizers or chemicals of any kind," said Alan Weene, spokesman for BioNova, which has partnerships to build natural swimming ponds in more than 30 countries. The BioNova system uses shallow- and deep-water plants in conjunction with filters to keep the water clear. The system only works to a temperature of 86 degrees, so it isn't suitable for hot tubs.

BioNova pools, as well as those designed locally by Environmental Sculpturing, are biologically active. That means unlike chemically treated pools, which are sterile, natural swimming pools contain plants and beneficial microorganisms that outcompete algae and harmful bacteria for nutrients, leaving water safe for swimming. Water is circulated with pumps to prevent mosquitoes from laying eggs.

Although installation costs are slightly higher for a natural swimming pond compared with a traditional pool, the level of maintenance is roughly the same. Both types of pools require vacuuming and hand skimmers to pick off surface debris. Natural swimming ponds do not need biweekly visits from a pool professional to add chemicals, but they do require occasional weeding and replanting.

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"One of the reasons why chlorine is the most popular swimming pool disinfectant is that it provides a long-lasting residual in the water," said Mary Ostrowski, director of chlorine issues for the American Chemistry Council in Washington, D.C. In response to rising consumer interest, Ostrowski said, the group is working with an advisory council to determine ways pool owners could reduce their chlorine use in conjunction with other technologies.


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