EcoWater CHC Series Service And Troubleshooting Manual page 96

Magnesium hardness (Mg): Mg, like Ca, is leached from the soil by rainwater. It contributes to the
total hardness but is generally present at much lower levels than Ca. Magnesium hardness is a
calculated number based on measured total hardness and calcium hardness:
Magnesium hardness = Total hardness - Calcium hardness
Total hardness: This is the sum of Ca and Mg hardness. Fe (Iron), Mn (Manganese), Al (Aluminum)
and other metals also contribute to the total hardness but these substances are usually present in such
small quantities that they can be ignored. Hard waters are generally considered to be those waters that
require considerable amounts of soap to produce a foam or lather, and that also produce scale in hot
water pipes, heaters, boilers, and other units in which temperature of water is increased materially.
The hardness of water varies considerably from place to place. In general, surface waters are softer than
ground waters. The hardness of water reflects the nature of the geological formations with which it has
been in contact. The following illustration shows the general character of the water supplies in the
United States. The softest waters are found in the New England, South Atlantic, and Pacific Northwest
states. Iowa, Illinois, Indiana, Arizona, New Mexico, and the Great Plains states have the hardest
waters.
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