Greg,
It does indeed measure to 1ppm in the 10 to 20 ppm range. From 20 to 30 it measures in about 2 ppm increments. Above that it gradually becomes less precise and 5 ppm accuracy is the best you can do above about 60 ppm.
The test is quite simple, a lot simpler than describing it, but I'll try. First, you obtain a 20 ml sample of water and put 6 drops of a green liquid (provided) in it. Each test has a glass ampule shaped like a syringe and a flexible tube that fits over the pointy part. The pointy end is broken and then placed in a titrating device that allows the sample to be drawn into the ampule by the user simply by pressing a lever. The ampule is already filled with a second clear solution and it is also a vacuum. As you draw the green solution into the ampule it turns a pinkish-red. Draw it in small amounts watching the color. When it turns back to green and stays that way, remove the ampule and invert. The alkalinity in ppm is determined by graduations on the side of the ampule. Wherever the liquid line is, there is your measurement.
It is almost impossible to screw it up and it measures most precisely exactly in the range that pondmeisters are interested in. It is far superior to test strips, and seems tailor-made for ponds. I've been extremely happy with it.
On a similar note, I just ordered my first pallet of Southern Excellence from Jerry Robinson. Springtime and lots o' work are upon us!
