Re: [APD] pH test meter recommendations

[Chris Hotte <ecwh at cogeco_ca>]

Shireen Gonzaga wrote:

> That's it, I've had enough of those damn pH test kits. Matching the 
> test solution to the color charts is a nightmare. I'm starting to see 
> things ... strange strange things that laugh at me and call me "stupid".

I know what you mean. The colour chart gnomes convinced me to switch to 
a numeric display as well. I forked out the cash, and trust me I'm one 
who has trouble making ends meet most of the time.  I purchased the 
nutradip PH meter. It has a probe that extends into the tank for 
continuous monitoring. The glowing LED segmented display sold me for 
certain. Like audio equipment, glowing lights in a dark environment are 
a sure sale for most men. Fitting the meter below in the dark receses of 
the cabinet floated in my head as I passed my visa over the counter.

I have not been dissapointed either. I just checked my receipt and found 
it dated 02/05/04, so it's over a year old.  The probe is still as quick 
to react as the day I bought it. I've been told they begin to slow in 
response and it's a sign for replacement. Placing the probe in a new 
solution usually reads 0.1PH high or low for 1-2 seconds and then locks 
in correctly.

On initial investigation I was dissapointed with the segmented display 
only being .1PH accurate. The Hanna hand held jobs could display %0.00 
precision which I wanted because CO2 is affected by small changes in 
PH.  Well, the clerk assured me that the display was not accurate, and 
certainly enough the paperwork for the hand held meter indicated the 
accuracy versus display capabilities were in fact not in sync with each 
other. It's accuracy was in fact 0.2ph where the nutradip with probe was 
.1ph accurate.

With a KH of 85ppm and difference of .1PH = 10ppm C02.

So I highly recommend a separate PH probe and even maybe the nutradip 
meter: http://www.growhere.com/testers/nutraphmeter.htm

(I still have the box)

Range: 0.0 - 14.0pH
Accuracy: +/- 0.1%
Resolution: 0.1pH
Calibration: 2 point, Manual
Operating environment: -20C to 80C
Demensions: 15.5 x  7 x 2.8 cm


In the end I still go back to my good old colour chart to check against 
the meter. I did it today because of my needle valve fiascle. See that 
post for details. I just calibrated the meter a couple days ago and had 
doubt that it was showing a pH of 6.5 correctly for fear I'd calibrated 
incorrectly.  Certainly enough when the pH came back up to 6.6 I took 
out my Aquarium Pharmaceuticals pH indicator solution and the colour 
indicator chart was BANG ON 6.6.

Moral of long story.... the colour chart gnomes don't really exist. No 
really. They don't. Trust me.  Unfortunately, this can only be proven 
with the addition of an accurate meter.  But don't throw out your pH 
indicator solution. No sir. You'll just end up where you started in the 
first place.

Just think, if we keep up with this hobby long enough, mother nature in 
her infinit wisdom and powers of evolution might just grant us 
sensitivity to potential hydrogen on our forefingers.

- Chris.

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