Total hardness is one of the water parameters that you need to check regularly to ensure you keep you pool in perfect condition. Total hardness is the measure of dissolved minerals such as magnesium, Sodium and Calcium in the water and is also known as Calcium hardness when referring to pools. High levels of Calcium hardness result in scaling of pumps, pipework and filtration equipment. If the level is low then the water becomes corrosive which results in etching of the pools surface and corrosion of metals in the system which can in turn create staining on the pools wall and floor.