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Re: total alkalinity and total hardness

> Date: Tue, 14 Oct 1997 00:56:24 -0700
> From: Stephen Pushak <teban at powersonic_bc.ca>
> I think I understand that KH measures carbonate ion concentration and GH
> measures total dissolved solids. 

TDS is not GH, as typically defined by aquarists.  GH is solely Ca and
Mg concentration. TDS includes other dissolved minerals such as
sulphur, sodium, etc.

> Knowing the total alkalinity and total hardness, and the
> concentrations of Cl-, NO3-, SO4--, Ca++ and Mg++ can we deduce CO3--,
> Na+ and K+ concentrations? (assuming typical ground water from a well)

I would suspect not, since you probably don't really know what those
concentrations are. 

> Here are the parameters (ppm):
> Chloride       45.
> Nitrate        22.2
> .
> .
> .
> Ph              7.1
> Total Hardness    280
> Total Alkalinity  330      

These are most likely averages over time taken at a specific point in
your water system.  Your values at any point in time and geographic
location may vary.  And these are typical tap water water values; once
the water is in your aquarium and subjected to fish food, fertilizers,
chemicals and substrate leaching, all bets are off. Also note that
there are various ways to determine or calculate "Total Hardness" and
"Total Alkalinity" and the values above may not relate to our perverted

I've attempted to do this using measurements from my array of LaMotte
test kits. Exhaustive discussions with Roger Miller convinced me of
the hopelessness of such an endeavor. 

George in Colorado