This kit has test for a correct pH and chlorine measurement. This is an essential product intended for a proper pool maintenance. It is easy and simple to use: Fill the yellow cap vial with swimming pool water to the marked line. Add 4 drops of solution called “OTO”; then cover and shake the mixture. After that, compare the resulting colour with the colour standards indicated on the plastic tester. These standards test the amount of combined chlorine and bromine of the pool. The ideal levels for clear, clean and disinfected water are indicated on the plastic tester (they must be between 0.6 and 1 ppm, in the case of chlorine, and between 7 and 7.5 for pH). Remember to test firstly the pH of the pool and, secondly, the chlorine.