Pool and spa test strips. Ideal to ensure your pool and spa has the right levels of chemicals. These 3-in-1 test strips test the following: free chlorine, pH, and total alkalinity. With an easy color-match system, you will instantly know what chemicals are in need of adjusting. The strips measure free chlorine from 0 to 10 ppm, alkalinity from 0 to 240 ppm, and pH from 6.2 to 8.4 with instant results. The bottle contains 50 test strips and has an 18 month shelf life.