Includes 50 x Clearwater dip test strips that make caring for your pool simple and easy. Measures chlorine, PH and alkalinity: Measures various quality levels of swimming pool or spa water to indicate what chemicals are needed to prevent harmful bacteria entering your water. Quick and easy to use - simply dip the test strips into the water and check the results on the handy printed colour chart. Directions: Dip strip and remove immediately, hold strip level for 15 seconds, use simple-to-use guide on bottle to read the results. Bishta approved UK brand: Clearwater is a BISHTA approved UK brand that is recommended by brands such as lay-z-spa and best way to help provide quality care to your pool or hot tub.