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Re: alkalinity

Dennis wrote:

> <<  The
>  tap water where I live is just like softened hard water, and I wonder what
>  chemical processes underground produced it.  It has no measurable calcium
>  with the LaMotte calcium test kit, and no measurable GH with the Tetra kit.
>  It has 9 degrees alkalinity (KH) with the Tetra kit, and the pH out of the
>  tap is 8.5. >>
> Yes my softened Tap water also gives the unbelievably high pH reading as
> well.  The interesting me to me though is that if let it settle for 3 days in
> a
> seperate container the pH reading drops to about 7.4?  Any idea what is
> happening here?

If your tap water comes out with a high pH (often over 9) and the pH drops
after its exposed to air, then your public water system probably uses a
bulk water-softening method (lime softening) that as a side effect strips
all CO2 out of the water and increases the pH to high numbers - sometimes
near 10.  Home water softeners don't usually change pH.  pH drops when its
exposed to air because CO2 from the air dissolves into the water. 

Paul's public system might use a treatment system as well, but the very
low hardness, high alkalinity and pH less than 9 suggests to me that his
water was altered by ion exchange softening, rather than lime softening. 

Roger Miller