Phosphate Test Kit gives accurate results after only 60-seconds, and measures phosphate from 0 to 1000 parts per billion. Includes directions in English and Spanish. Quantity of 20 tests per bottle. Use the most accurate method for phosphate testing: a one step, one minute, phosphate test. Even very low levels of phosphate can feed algae and create problems in pool water. Test for phosphate once a week as the concentration in the water can increase rapidly due to rain, debris or bather load. Results in a minute! For a clean and healthy pool, test the water at each end a minimum of twice a week! *Phosphate product only available in US.