Water balance is important as it ensures that the mineral content of the water is in an appropriate state to protect the pool surface and equipment and make water more comfortable to swim in. Water balance is affected by a wide range of variables – the quality of the source water, what chemicals are added to the water, the exposure of the pool to weather conditions and so on. A proper balance of chemical factors such as total alkalinity, pH and calcium, is needed for the sanitiser to work correctly, the water to be pleasant to swim in, and to prevent scaling or corrosion of the pool surface and equipment.