It looks like a conventional pool but is in fact a fully-fledged biological pool.

The Biotop Swimming Pool looks like a conventional pool but is in fact a fully-fledged biological pool which requires absolutely no chlorine or other toxic chemicals and offers the ultimate in swimming enjoyment in crystal clear water. Instead of a regeneration zone with the plants and wildlife that are required by a natural pool, a biofilter and a specially developed phosphorous filter treat the water on a biological and physical basis.