RE: Micro-s vs. TDS

["Tranquility Base" <TranquilityBase at NetZero_Net>]

Hi Boat,

I have neither meter. So I can't actually tell you what the readings should
be. But theoretically TDS and conductivity are two very different things.
Conductivity is a measurement of how well water conducts electricity.
Distilled water is either nonconductive or practically nonconductive, the
more conductive solids dissolved or ionized in it the more conductive the
water becomes. Certain salts that ionize in water make water very
conductive, very quickly. On the other hand, if you were to dissolve
something nonconductive in water it would not increase the conductivity
nearly as much. Depending on what material is dissolved in the water
conductivity may not be a true measurement of TDS. The proper way to
determine the true TDS is to evaporate the water and weigh the resultant.
The most common TDS meter is actually a conductivity meter. The TDS meter
relies on the typical correlation between TDS and conductivity based on an
assumption of what us usually found dissolved in water. As table salt
ionizes in water it makes water very conductive even in small amounts. This
is why adding salt to the aquarium water causes TDS meters to read so high.

So in theory, at least, the TDS and the conductivity need not be identical.
I am sure the chemistry types on this list can due a better job at
explaining this.

Peace,

~RJ~

-----Original Message-----
From: owner-killietalk at aka_org [mailto:owner-killietalk at aka_org]On
Behalf Of Allen Boatman
Sent: Friday, May 03, 2002 7:53 AM
To: killietalk at aka_org
Subject: Micro-s vs TDS


I am confused. (an admition)  Ron quoted a collection report from Africa
that said:

"TDS 20     µSi 0.03"

How can the TDS be 20 and then the Conductivity (Micro-S) be 0.03?

I would think it would be more like 40 or 45.  Can someone please "splain"
it to this ig-no-ray-moose?

Thanks,
Boat

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