How to manage calcium hardness levels in pools? Calcium is a naturally occurring mineral that is frequently found in high concentrations: such water is called “hard” water. Calcium hardness chemistry is one of the important pool water parameters and its control is important, to help assure proper water quality and help avoid certain pool water problems. The preferred ranges, in swimming pools, are 80-150 PPM in a vinyl pool and 150-200 PPM in a masonry finish pool. Low levels of pool water calcium hardness (soft water) can lead to the problms of corrosive water conditions. Chemicals are available to raise the calcium hardness, as might be necessary. High pool water calcium hardness levels, especially above 400 PPM, can lead to possible pool water clarity problems and scaling conditions. Chlorine products containing calcium hypochlorite raise the hardness level, each time the product is added. Discontinuing such product usage can help avoid further unwanted increases in the calcium hardness. Various chelating or sequestering Mineral Treating Products are available to help deal with the problems associated with high calcium hardness levels. Pool water calcium levels can be determined by a simple water analysis. This is especially important with well water, as other problematic minerals might be present and could require treatment. Pool Water Magnetizers, also called Magnetic Water Conditioners, have been reported to help reduce and eliminate scale formation, by inducing a positive electrical charge in the water passing through the return lines.!