Bests & Worsts Reviews from Amazon

I just received this today; so I cannot speak for long term reliability. However, it worked great right out of the box. I tested the following samples: Pool Water, Water from my kitchen tap, water from my filtered refrigerator, bottled spring water, and distilled water. The distilled water was the first that I tested and it had a reading of zero; as expected. Each time that I tested a sample, I put the tester back into the distilled water to clean it and retested the distilled water. As I progressed through my testing and cleaning cycle, the distilled water rose slightly (1 to 2 ppm) with each rinse. I tested all samples twice and got the same result; meaning this this is consistent. The distilled water rose to 5 ppm after rinsing from the first test cycle and was at 12 ppm after my last test cycle. I expected some rise in ppm since I was cleaning off hard water into the distilled water; I think this is a very good representation of the accuracy of this tester. As I final test, I tested a fresh glass of distilled water and it had a reading of zero. I think I did a pretty thorough job of testing the accuracy of this tester and I was very pleased with the results. I also tested temperature of my five samples after they had been sitting for about 20 minutes; all of them were within 0.5 degrees F. So far, this tester does exactly as it should and I am now very confident in it's accuracy. It seems to be built fairly well and it has a nice carry case with it. As I said in my headline; "It's a winner".