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Re: New TDS Meter - Questions!
Jay-Scott Moylan wrote:
> Makes sense. Charles Harrison advised the same. Is R/O water free
> of dissolved solids? Obviously distilled water is, but what tds
> concentration would R/O have if any?
The latter depends on how hard (actually high in tds) the original water
was, and how good your system is. My old one gave me 50 ppm from 450 ppm tap
for many years (>10 yrs.). My new one takes my 300 ppm+/- down to below 10
ppm. It has more filters and is a better membrane, I think. It's called a
"5-Stage" RO System.
You can buy cheap distilled, de-ionized, and RO water at most grocery
stores. Those three are in order of increasing tds, most of the time.
Distilled and DI will usually measure at or very close to zero on a tds
meter. RO usually has a measurable residual, but very low.
If you are good at arithmetic, you can use *any* measurable water (well
below 999 ppm) to dilute your unknown, and calculate the tds of your
unknown. It's way easier if the diluent is very low or negligible tds to
You will be well within the right ballpark, if you use RO and just subtract
the measured RO tds from the final reading of the diluted mix, before
multiplying by the dilution factor.
Wright Huntley, Fremont CA, USA, 510 494-8679 wright at killi dot net
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