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Re: deionized vs RO
In a message dated 6/24/99 9:22:21 AM, huntley1 at home_com writes:
<< 99% of reported "pH-shock" cases were probably from sudden drop in tds. >>
Actually, as Wright points out the tds is only indirectly related to the
crucial value of osmotic pressure. Since all colligative properties are
quantitatively related, a measure of the freezing point or boiling point
would more accurately relate to the osmotic pressure, BUT, the differences
are too small to measure without very accurate apparatus and thermometers.
What the aquarist needs is a little pocket meter that reads osmotic pressure.
In lieu of that the conductivity meters are the next best thing. As hge also
points out, the direction in which the change occurs is crucial - going to
higher tds, conductivity, osmotic pressure or hardness is less stressful than
going to lower values. This is why adding a little salt to water that is
receiving new fish always helps, along with slow acclimation.
Lee Harper