In testing for Chlorine/Bromine in a commercial pool, why is DPD preferred over OTO?

In testing for Chlorine/Bromine in a commercial pool, why is DPD preferred over OTO?

• A. DPD tests for free chlorine only
• B. OTO only tests for Total Chlorine
• C. DPD is less expensive
• D. Both are equally effective

Answer: (B)

DPD is preferred over OTO in testing for chlorine and bromine in a commercial pool primarily due to its ability to measure both free chlorine and total chlorine accurately. The DPD method provides a colorimetric test that can distinguish free chlorine's presence, which is crucial for assessing the disinfecting strength of the water. Free chlorine is the form that actively works to neutralize pathogens, while total chlorine includes both free and combined chlorine. The OTO method, on the other hand, primarily measures total chlorine and cannot differentiate between free chlorine and combined chlorine (chloramines). This lack of specificity means that while OTO can indicate the presence of chloramines, it does not provide the critical information about free chlorine levels needed to ensure water safety and effective sanitation. In practice, having an accurate measurement of free chlorine concentration is vital for pool operators to maintain appropriate disinfection levels, which is why DPD is the preferred testing method in commercial settings.

DPD is preferred over OTO in testing for chlorine and bromine in a commercial pool primarily due to its ability to measure both free chlorine and total chlorine accurately. The DPD method provides a colorimetric test that can distinguish free chlorine's presence, which is crucial for assessing the disinfecting strength of the water. Free chlorine is the form that actively works to neutralize pathogens, while total chlorine includes both free and combined chlorine.

The OTO method, on the other hand, primarily measures total chlorine and cannot differentiate between free chlorine and combined chlorine (chloramines). This lack of specificity means that while OTO can indicate the presence of chloramines, it does not provide the critical information about free chlorine levels needed to ensure water safety and effective sanitation.

In practice, having an accurate measurement of free chlorine concentration is vital for pool operators to maintain appropriate disinfection levels, which is why DPD is the preferred testing method in commercial settings.