Just dip an AquaChek Red strip in your spa (hot tub) or pool water for one second and remove it immediately. You get test results in seconds! To keep your spa at its best, test the water before each use. (Two bathers in a 400-gallon spa are the equivalent of 150 swimmers in a 20,000-gallon pool!) Test your pool at each end a minimum of twice a week. It’s also a good idea to write down your results each time you test. Comes with complete instructions. 50 strips per bottle. AquaChek Red has added directions in 15 Languages to the product insert! English, French, Spanish, Italian, Czech, Danish, Dutch, German, Greek, Hungarian, Polish, Portuguese, Russian, Swedish and Turkish.