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Re: Aquatic Plants Digest V3 #89

Paul K. wrote:

> and this will give a low or no GH value, but still a high KH value.  The
> tap water where I live is just like softened hard water, and I wonder what
> chemical processes underground produced it.

Well, this is something of a tangent, but...

It's probably produced naturally in the same way that it's produced
artificially - by cation exchange.  I don't have first hand knowledge
about conditions in central Mississippi, but in all other cases I know of
the condition is created when water moves long distances through a sand or
sandstone aquifer.  Clays (and sometimes zeolites) in the sandstone were
charged with sodium when they were formed.  As water passes through the
sand, the calcium and magnesium in the water is traded for the sodium in
the clays.  That produces water that is very soft, but usually has
moderate to large (for potable water) amounts of other solutes. 

Roger Miller