Natural swimming pools are the biggest news for gardeners since green roofs. The water is cleaned by aquatic plants instead of chlorine so it is gentle on the eyes and healthy for swimmers. These self-cleaning ecosystems are beautiful to look at and provide a valuable water source for dragonflies, honeybees, and other beneficial insects. Wolfram Kircher has researched extensively into the low-nutrient-dependent plants that are needed for the surrounds of natural swimming pools and the high-nutrient-dependent plants that are required for the regeneration zone. In the book he demonstrates how to maintain the nutrient level in perfect balance to keep down the algae and water sparkling.