Natural swimming pools rely on the correct balance of living plants and micro-organisms to clean and purify the water. They are easy and less costly to maintain than chemical pools. Chlorine and other common pool chemicals that are hazardous to human health are not used. Natural pools are safe places for children to play and birds to drink, and are a dramatic example of ecological design, combining the natural and man-made worlds while creating beauty. These pools offer enjoyment not only in the warm months, but during winter, when they can be used for ice skating. Often the focal point of a...