Used this product to test my hot tub water. It seems to be pretty accurate, however, I find that the outer edges of each testing square, seems to have a slightly different colour than the middle of the square. In all fairness, it seems to be consistent with all of these types of testers I plan to use it to test the salt water pool as well in the summertime so we’ll see how that works. I like that I get three times the amount of testing strips (150) then with other manufacturers for the same price. I’m looking for a digital tester to test bromine/chlorine, pH and alkalinity to avoid having to buy these test strips and see if it’s more accurate. It will also leave less room for misinterpretation.