Is a DPD liquid pool tester more accurate?
The DPD test for chlorine can be affected by interferences, such as an overabundance of mono-chloramines or potassium mono-persulfate (used for shock-treating pools). These can give a false positive reading for free chlorine with the DPD chemistry. In addition, the DPD test requires careful technique and several steps to obtain the best test results. Some of the better test strips will test for Free, Total and Combined chlorine, just as the reagent style of dropper bottle test kits do.
