Review on Industrial Test Systems Poolcheck 481333 by George Kapoor

I have used a number of products for industrial testing systems and have found them to be fairly accurate. It's close enough to ensure I have about + or - the right amount of borate to do my job of buffering pool chemistry. The gradient around the right amount (50 ppm) goes from 25, then 50, then 100 ppm. The color difference from 25 to 50 is quite noticeable, but from 50 to 100 is only a minor change to me. I went to 25, then added a few pounds, then checked the next day, added a few more, checked the next day, etc. until I hit 50ppm and didn't add anything more at that point.