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ETC ENVIRONMENT TECHNOLOGY CENTER
ETC Water Softeners
What is Hard Water ?
Hard water is the most common problem found in the average
home. Hard water is water that contains dissolved hardness minerals
above 1 GPG.
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How do you Measure
Hardness ?
Water Softeners Parts per million or grains per gallon are the most common. One part per
million (PPM) is just what it says: out of one million units, one unit.
Grains, or grains per gallon (GPG) is a weight measurement taken from the
Egyptians; one dry grain of wheat, or about 1/7000 of a pound. It takes 17.1
PPM to equal 1 GPG.
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Deionization
Used mainly in labs, manufacturing processes, or for serious aquarium
owners, DI filters are actually more complex than a filter. True filters,
unlike the selective resin and DI units, work on a mechanical basis: they
just 'catch'the particles that are too large to fit through the spaces
between the filter media. (Well, I fibbed a little; but who wants to know
about the Van Der Waals or Coulomb forces?) DI works by ion exchange, just
like a water softeners. Just as a water softeners exchanges sodium
for hardness minerals, a DI unit will have two types of resin in it:
Cation and Anion. Basically, the Cation resin (like in a water softeners)
removes the ions with a positive charge, while the Anion resin removes those
ions with a negative charge. Instead of using salt as a regenerant, acid and
caustic are used. Some small DI cartridges are sold as "throw-aways", others
can be returned for regeneration and reuse. These small units can treat only
small amounts of raw, citywater. Usually, it is much more economical to
pretreat the feeding a DI system with reverse osmosis water.
Water Softeners Systems-Water Softener-Water Softeners