DPD tester for free chlorine/pH

Tester is used to test Oxygen and the pH value of pool water. To keep your pool water crystal clear, its use is essential. First measure the pool water values and if they are not within the norm (pH 6.9-7.4 ; O₂ 3.0-8.0 mg/l), adjust the pool water using pool chemicals. First adjust the pH value (pH+ or pH-) and subsequently adjust the Oxygen value  (only increase - if the chlorine value is too high, do not decrease it, in a few days it will drop on its own). Oxygen is applied only after pH regulation because the effectiveness of Oxygene outside the recommended pH range rapidly decreases.
Tester DPD works on the principle of visual comparison with a color chart next to the sampling chambers - after adding tablets (OXY/pH) the water colors, according to the results it is necessary to adjust the OXY/pH value in the pool.