White Cloud is a lime stone, which consists of bio- turbated muddy lime. Stone is very well packed and contains therefore low porosity and permeability. The calcite crystals are embedded in the very fine muddy lime, so protected against external chemicals, making it suitable for swimming pool applications. The high percentage muddy lime gives the stone a certain degree of flexibility making it suitable for paving and drive way applications. Precipitation on top of the stone may occur if the water is hard , air pollution is strong and water circulation/ filtering inadequate. Especially saltwater pools need good chemical balances.