DescriptionAquaChek Chlorine, testing for: Free Chlorine, pH, Alkalinity and Cyanuric Acid (only applicable to swimming pools).Just dip an AquaChek Yellow strip in your spa water for one second and remove it immediately. You get test results in seconds!To keep your spa at its best, test your spa before each use. It’s also a good idea to write down your results each time you test, so you can track changes in your water as you gradually adjust your chemical balance.50 Strips Per Bottle