Culligan Aquasential Select Plus Series Owner's Manual page 10

Why Water Gets Hard And How It Is Softened
All of the fresh water in the world originally falls as rain, snow, or sleet� Surface water is drawn upward by the sun, forming
clouds� Then, nearly pure and soft as it starts to fall, it begins to collect impurities as it passes through smog and dust-laden
atmosphere� And as it seeps through soil and rocks it gathers hardness, rust, acid, unpleasant tastes and odors�
Water hardness is caused primarily by limestone dissolved from the earth by rainwater� Because of this, in earlier times people
who wanted soft water collected rainwater from roofs in rain barrels and cisterns before it picked up hardness from the earth�
Some localities have corrosive water� A softener cannot correct this problem and so its written warranty disclaims liability
for corrosion of plumbing lines, fixtures or appliances� If you suspect corrosion, your Culligan dealer has equipment to
control the problem�
Iron is a common water problem� The chemical/physical nature of iron found in natural water supplies is exhibited in
four general types:
1. Dissolved Iron – Also known as ferrous, soluble or clear water iron� Dissolved iron is soluble in water and is
detected by taking a sample of the water to be treated in a clear glass or white Styrofoam cup� The water is
initially clear, but on exposure to the air it may gradually turn cloudy or colored as the iron oxidizes� Up to 5 ppm
of this type of iron can be removed from the water by the same ion exchange principles that remove the hardness
elements of calcium and magnesium� Dissolved iron is the only type of iron a water softener will reliably remove�
2. Particulate Iron - Also known as ferric iron or, rust� This type of iron is an undissolved particle of iron� A
softener will trap some of the larger particles of iron, but many will not be flushed out of the resin bed during the
regeneration cycle� This will eventually lead to an accumulation of particulate iron in the resin bed and to service
and foul the ion exchange resin� A pre-filter will be required to remove this type of iron prior to the water softener�
3. Organic Bound and Colloidal Iron – Organically bound iron is strongly attached to organic matter in the water�
The ion exchange process alone cannot break this attachment and the softener will not reduce it� Colloidal
particles will also not exchange onto softening resin are too small to be removed by conventional filtration�
4. Bacterial Iron - This type of iron is protected inside a bacteria cell� Like the organic bound iron, it is not removed
by a water softener�
When using a softener to remove both hardness and dissolved iron it is important that it regenerates more frequently
than ordinarily would be calculated for hardness removal alone� Although many factors and formulas have been used to
determine this frequency, it is recommended that the softener be regenerated when it has reached 50–75% of the calculated
hardness alone capacity� This will minimize the potential for bed fouling� (Iron removal claims have not been verified by the
Water Quality Association�)
If you are operating a water softener on clear water iron, regular resin bed cleaning is needed to keep the bed from coating
with iron� Even when operating a softener on water with less than the maximum of dissolved iron, regular cleaning should
be performed� Clean every six months or more often if iron appears in your conditioned water supply� Use resin bed cleaning
compounds, carefully following the directions on the container�
NOTE!
Do not use where the water is microbiologically unsafe or with water of unknown quality without
adequate disinfection before or after the unit.
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