Hardness Reduction

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The seven key minerals that make up most rock formations in the United States are divided into two groups: cation and anions. Cations are positively charged minerals and include calcium, magnesium, sodium and potassium. Anions are negatively charged minerals and include carbonates, sulfates, and chlorides. Each type of rock has an equal number of cations and anions, and so does each water supply. 

When we discuss “hard water” we are referring to a water supply with a concentration of the four hard minerals: calcium, magnesium, carbonate, and sulfate. These minerals are components of the hard rock formations that we call lime shale and gypsum. 

Mineral deposits such as limescale create major problems for food service operations that use ice, coffee, espresso, steam and warewashing equipment. Mineral scale can clog tubing and small orifices, coat heating and cooling elements, and result in increased detergent usage. Scale also causes reduced energy transfer and efficiency loss, resulting in increased energy demands for cooling or heating, and increased operating costs. Increased operating costs include the need for deliming — an acid cleaning process that removes mineral scale. This process is harsh to the equipment surfaces and decreases equipment life. 

Hard water with a high pH can be treated with a water softening system or a reverse osmosis system. 

Hard minerals such as calcium and magnesium, when evaporated from water or combined with heat, can form hard, chalky deposits known as limescale. These deposits can clog pipes, reducing flow, and coat heating elements, requiring more energy to heat water. Your operation loses efficiency, and your maintenance and energy costs rise. 

There are different means of treating scale, such as phosphates, reverse osmosis and softening. Each treats for scale differently, for example phosphates keep mineral suspended in solution, reverse osmosis removes mineral, and softening exchanges hard mineral for soft mineral (such as sodium). Softening provides both advantages and disadvantages. An advantage is a maintained softener can provide hardness removal for many years and models can handle high volumes of water. A disadvantage is sodium must be added to the brine tank on a regular basis. 

Measuring Grains of Hardness 

Hardness of water is measured in grains per gallon (GPG) or sometimes in parts per million (PPM). One GPG equals 17.1 ppm (Mg/l). Generally water with GPG of 7 or more is considered hard. To determine the hardness of your water, it can be tested using simple test strips or a titration drop test. 

Pentair Everpure® can provide an analysis of your water to determine the correct water treatment solution for your operation. 

Water               Grains / Gallon   Mg / l or ppm  

  • Soft                          < 1.0                    0 - 17.1  
  • Slightly Hard             1.0 - 3.5            17.1 - 60  
  • Moderately Hard        3.5 - 7.0              60 - 120  
  • Hard                        7.0 - 10.5           120 - 180  
  • Very Hard                  > 10.5                 180 +  

Hardness Reduction

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