On Thu, 11 Mar 2004 12:29:11 GMT, "Michi Henning"
wrote:

"NetMax" wrote in message
...

I don't know the mechanism at work when water is softened by boiling, so
the effect may not be permanent, or perhaps it changes state so it does
not register with the test kit and perhaps the fish (?).

As far as I know, boiling causes the bicarbonates in the water to
precipitate out. This releases CO2 and binds some of the kations,
such as Mg and Ca. Since a GH test measures kations, GH drops.
And because CO2 is driven out, pH rises, and KH drops. If you
run CO2 through the boiled water, the previous balance quickly
re-establishes itself.

Cheers,

Michi.


with a bit of variation.

bicarbonate hardness, also called temporary hardness, can be reduced
by boiling. The calcium and magnesium bicarbonates are converted to
calcium and magnesium carbonates, much less soluble, which settle out
on the boiling container as lime scale. if the boiled water is then
moved into a separate container, the calcium and magnesium carbonates
are left behind and the total hardness has been reduced.

so called permanent hardness is from calcium and magnesium sulfates
which are unaffected by boiling.
--

- Charles
-
-does not play well with others