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Re: [APD] How to make a good KH reference stock solution for CO2 measurement

On 12/13/06, Vaughn Hopkins <hoppycalif at yahoo_com> wrote:
> I'm not disagreeing with your approach, just pointing out that I
> don't need a micrometer to measure the thickness of a pine board.


I don't know about anyone else's KH kit, but mine is an Aquarium
Pharmaceuticals kit that's about 2 years old.  I expected it to be off by
quite a bit because it is 2 years old and decomposition of the solution
could be an issue.  So when my new water supply turned out to show a really
low KH I was a little surprised because decomposition would likely cause a
reading that was higher than the real value, rather than lower.  So I made a
stock solution and was shocked to discover the number I got from the kit was
within the error associated with making the stock solution.  For all
practical purposes the kit was dead on.

With regards to digital scales, they also have to be calibrated and few of
them are designed for a home user to calibrate.  Further, most folks don't
have a known mass to use for calibration.  I have a large number of 1.0 oz
silver coins along with a few 3.0, 5.0 and 10.0 ounce coins. I used them to
discover how accurate my digital scale really is.  It is off by 10% over a
range from 1 oz to 4 pounds.  The most surprising finding to me was that the
error was constant over that range, which is pretty danged good for a
consumer scale.
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