Too High

• Too much calcium and magnesium can result in a scaly buildup on the sides of the pool and eventually plug the piping, pump and other equipment. It can also lead to eye irritation in the swimmers.
  
  

Too Low

• Too low hardness levels can result in scarring and pitting of the pool surface and corrosion in the equipment, such as the pump and piping.
  
  

Recommended Level

• The hardness test should result in a measurement of at least 200 ppm but no more than 400.
  
  

Resolution

• If the level is too low, add calcium chloride. If the level is too high, remove some of the water and add fresh. Don't forget to retest afterward.
  
  

Other Applications

• Water hardness tests are also run on drinking water. Water with a hardness of 120 ppm and up is considered hard water when it comes to consumption.