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RE: Colorblind Testing

> Statistically, there have to be a few dozen colorblind people on this
> list. I was wondering if anyone knows of any test kits for Ca or GH that
> are readable for us colorblind folks. I am having a hard time
> determining my Ca levels. Turning from light green to an orangish-red is
> not detectable to a red-green colorblind individual - nor is light blue
> to light pink as GH and Ca tests generally are respectively.

I'm red-green color blind. My ability to detect the subtle changes in color
from most hobbyist test kits is almost zero.  For example, I couldn't see
the difference between pH 6 and 8 in the first cheap pH test kit I bought.
My solution was to first buy a good pH Wand from Cole-Parmer (actually made
by Oakton).  This is microprocessor controlled and has ATC plus auto
calibration.  This gives me pH +/- 0.02.  I calibrate it at 4,7, and 10 (or
rather I make it calibrate itself) once a month.  The electrode comes with a
storage bottle and the reading is really rock stable.  For Alkalinity I got
LaMotte 4491-DR.  This is a direct read titration with the most obvious
color change I've seen in any test kit.  This gives me KH +/- 4 ppm.  With
pH and KH, I can look up my CO2.  For total, Ca, and Mg Hardness I got a
LaMotte 4824-DR-LT.  This is another direct reading titrator.  Total
hardness is clear for me, Ca hardness is a little tougher but I manage.  The
other test kits that I can actually read are:

      Phosphate (LaMotte 3121)
      Nitrate (Hach NI-114)
      Iron (Hach IR-21)

These all ask for a color comparison but come with a nice comparitor
(LaMotte) or color wheel (Hach).  I tested myself by preparing standards and
getting my girlfriend to switch the order of the standards.  I can usually
get the order (low to high concentrations) right, though I am usually
systematically high or low.  It helps to have a standard light source.  I
use the light from my metal halide reflected off a piece of flat
high-whiteness paper.

While I know my color preception is bad, I have not been impressed by many
of my (non-color blind)friends abilities to read test kits.  I takes some
practice and calibration to gain confidence.  Try making low, medium, and
high sequence in a known ratio.  For example, dissolve a calcium pill in a
gallon of deionized water and dilute it 4:1 and 8:1 with more DI water.

Joe K

It's turned cold here in Maryland.  Cyclamen Coum, crocus, Grape Holly and
Quince were blooming; are now frozen.