Increases the calcium hardness of the spa water. Helps to prevent foaming and equipment corrosion. The standard range measurement of calcium salts contained in the water is recommended at 175-225 ppm. Anything above this range could cause the water to be cloudy and/or scaling on the tub surface, equipment and piping. To increase hardness add Hardness Plus; to reduce hardness partially drain and refill spa. Spa Sauna Direct can not ship orders for pool chemicals or spa chemicals outside of the continental United States.