Comments:
I don't like it. It has the standard axial-read comparator, which works just fine in other low-level test kits from Lamotte. But there's a warning that you must read it in sunlight, not artificial light. OK, that's reasonable, the lighting spectrum may matter, since the color sample isn't exactly the stuff in the test tube.
Problem: the color sample is nothing like the solution in the test tube. Under any light, at any concentration I've run a test on, the hue of the samples is quite different from that of the actual test solution. It's extremely hard to compare the concentration (i.e., the saturation of the colors). If you're color blind, it may work fine -- seriously.
If I want a result I can rely on, I actually run a parallel test against a known solution. Extract measured amounts of solution from the darker sample till the color matches, and do the math. Yuck.
Worst of all, I don't know of a better test kit for these concentrations, 1 ppm plus or minus.
Note: the kit is a few years old (but not deteriorated), used in freshwater testing.
(Expertise listed below: in chemistry & test kits, not in fishkeeping.)
I would not recommend this product to my friends.
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