Randy,
I'm talking about the calcium test kit.
Our local club recently did a comparison study of numerous calcium, alkalinity, and pH kits. We found the alkalinity tests are all about the same in terms of relative accuracy among each other. We found no such correlation among the calcium test kits. There was a range of nearly 200ppm Ca++ between the test kits. My Hach kit read 505ppm Ca++ while the SeaChem kit read 350pmm Ca++. We believe the sample was around 375ppm Ca++, although we do not know exactly.
I tested my tank water with my Hach kit and a different model Hach kit from my LFS. My kit read 456ppm Ca++ and the LFS read 384ppm. That's a big difference. My kit is internally consistant. That is, it is always off by the same amount. I could be doing the calculations wrong or something, but it seems unlikely. The chemists in the club confirmed the calculations should be correct.
Any way, my original point was the color change in the hach calcium kit is very crisp. Very easy to read.
-Tom
[ February 15, 2002: Message edited by: pez ]</p>
