The invention relates to a method of treatment of bodies of water such as recreational pools, spas and hot tubs with maintenance doses of water treatment chemicals to achieve consistent sanitization and aesthetically pleasing levels of properties such as turbidity. The amount of the maintenance doses is based on the volume of water to be treated in order to achieve hygienic and clear water. The method can be automated for accurate, consistent and safe treatment of water such as found in swimming pools, spas or hot tubs.