How to measure the amount of UltraShock with the Poollab photometer? Am I right in assuming that UltraShock is measured as chlorine dioxide? If this is true, my question would be up to what concentration the water can be used or reused after use? The values at the Poollab are given in ppm for chlorine dioxide, but with the shock test strips in "Shock|ph" from my whirlpool supplier, they are given in mg/l. When I added 65 ml UltraShock to 1300 l water in my pool this morning, I had a value of 1.47 ppm ClO2 after half an hour with the Poollab photometer using the chlorine dioxide measuring method. With the test strips the value was 0.3 mg/l. For both methods, the limit values for use or reuse would be of great interest.
Answer:
UltraShock contains two types of chlorine which react with each other in the whirlpool when they come into contact with the water and permanently produce chlorine dioxide. This is why UltraShock can be measured with any chlorine measuring device. You can therefore measure the free chlorine with DPD1 and the total chlorine with DPD3. And from this difference the combined chlorine.
You cannot measure the chlorine dioxide. Due to the presence of free chlorine, combined chlorine and chlorine dioxide, the measurement results for the chlorine dioxide are falsified.