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Re: I thought I understood water hardness...

Paul Evans writes:

> GH the non-carbonate hardnes i.e.
>  the positive metal ions other than 
>  calcium and mangnessium.

Nope.  GH hardness is the measure of ions with a valence of +2, which includes
calcium and magnesium.  In fact, in most natural waters, calcium constitutes
about 90% of non-carbonate hardness, and magnesium makes up the vast majority
of the other 10%.
>  My confussion started last night.  I got a 
>  ion exchange water softener for my house.
>  Not for the fish tanks.  On a whim I decided
>  to measure the hardness of the softened water.
>  This is what I got.
>  KH = 9 degrees
>  GH = 1-2 degrees.
>  I thought the ion exchanger was supposed to
>  exchange sodium or potassium (potassium in 
>  my case) for magnessium and calcium thus 
>  reducing the carbonate hardness (KH) and
>  generally leave the non-carbonate hardness (GH)
>  alone.  Where have I gone wrong?

Carbonate hardness (KH) is the measure of CO3 (carbonate) ions.  The GH has
gone down because, as you rightly surmise, the Ca and Mg are being replaced
with potassium.  Your confusion comes from having the terms "general" and
"carbonate" switched.

Bob Dixon

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