Re: [APD] question about general hardness and water quality statistics

[Jamie Johnson <Jamie_Johnson at gel.com>]

> Ten years ago there was a really good discussion of water hardness and 
> alkalinity on this list.   I don't know if any of those people are 
> still around.   Don't expect their e-mail addresses from ten years ago 
> likely work.    I need some clarification.
>
> According to my tests of water fresh from teh tap, using API's test 
> kits, my GH is 143 ppm, and my KH is 5 dKH or 89.5 ppm.   Nearby 
> aquarium stores tell me their KH is 6 and 10.
>
> I understand that total alkalinity in the city's water quality reports 
> is measured the same way as KH in the aquarium test kits and 
> effectively is the same thing for all practical purposes.
>
> Total alkalinity from teh water quality reports is 70 ppm.   This 
> works out to 4 dKH.   (German degrees)
>
> Totally unclear is what figure on the water quality reports should be 
> the 'general hardness" or how to calculate it from what is there.
>
> Here are relevant statistics.
>
> Calcium 13.1 ppm
> Magnesium 15.6 ppm
> Hardness as Ca/Mg 105 ppm
> Total Hardness as CaCO3 70 ppm
> Total Dissolved Solids   175 ppm
>
> I THINK that the "Total Hardness as CaCO3 is the general hardness, but 
> it sure ain't 143 ppm.   And the range on that is only 87 - 113 ppm.

Dora, water hardness can be calculated from the Ca and Mg concentrations 
(Ca ppm x 2.497) + (Mg ppm x 4.118), which in this case is calculated to 
be 97 ppm. Maybe they did a titration test and got the 105 ppm value. It 
can be determined either way. It's hard to say. Alkalinity is reported 
as ppm of CaCO3. I think in this case, total hardness is really the 
alkalinity, where hardness is the GH.

Jamie <"///><



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