Re: NANFA-- Fishy observations

Bruce Stallsmith (
Tue, 06 Mar 2001 15:18:34 -0500


>Here's an unrelated tidbit. I, along with a few others on this list,
>purchased the Hanna Total Dissolved Solids meter which was (and
>still is) available for $14.99. I assumed that I could use this meter
>as kind of a substitute for a hardness test kit (which I do not own).
>Although I have had fun with it, nothing could be farther from the
>truth! In preparation for collecting more bluenose shiners this
>spring, I bought some water softener pillows from Mark Binkley
>(AKA "Jonah") and used them in my indoor 34 gallon native tank.
>Now, I had previously tested welaka water at 13ppm TDS (!)*, and
>this tank read around 350ppm, so I thought I needed to soften the
>water. The pillow should have removed around 150-200 ppm of
>hardness, but after the first use the TDS reading had not changed.
>Ha!, I thought, since it is replacing calcium ions with sodium, what
>should I have expected? Indeed, after I recharged the resin and
>replaced it, still dripping with the strong salt solution I had
>immersed it in, my TDS level DOUBLED to over 700ppm within 24
>hours. This should have come as no surprise, since the calibration
>solution sold by Hanna Instruments consists of KCl. But now it
>seems I need a hardness test kit after all...
>* For those who are interested, D.O. was a mediocre 7ppm, and
>pH was an astonishing 9.2 (questionable, since the meter was not
>calibrated that morning).
>Jackson, MS

Martin, you discovered a tough piece of chemistry--hardness and TDS are
different but related concepts. TDS is purely a measure of conductivity,
with a generalized interpretation of what causes the conductivity. Hardness
is caused by a short list of cations. I own the Hanna TDS meter which is a
great bargain, and last week I finally got the pHep 2 pH pen, with temp.
compensation and an accuracy of +/- 0.1 pH. It's a nice piece of equipment
for $50.

I really liked the Strong River when we visited last August, a more relaxed,
longer visit would I'm sure yield interesting fishes (hopefully with no one
drowning their car alarm control!).

--Bruce Stallsmith
Huntsville, AL

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