What is a DPD Reagent for swimming pools?
A DPD reagent, also called a DPD-1 reagent, is a chemical used to react with water when testing oxidizer concentrations. The official name for DPD is N,N Diethyl-1,4 Phenylenediamine Sulfate. DPD reagents is stable and has long useful life; and comes in a variety of configurations such as tablets, powder pillows, liquid bottles found in test kits, and as pads on test strips.
Chlorine, bromine, and chlorine dioxide are common oxidizers to which a DPD reagent will react. There are several DPD reagents available which perform different functions:
- DPD-1: Helps in testing common oxidizers like free chlorine, bromine, and chlorine dioxide.
- DPD-3: Added to DPD-1, and helps in testing total chlorine and ozone water levels.
- DPD-4: This is a mixture of DPD-1 and DPD-3.
Having a color chart is important when performing a DPD test, as the water sample color needs to be compared to the color chart to gauge the approximate oxidizer concentration. Typically, adding a DPD reagent to a water sample will produce a red tint in the mixture. Low to medium concentrations will turn light pink to strong pink. High to excessive concentrations will turn deep reddish orange, with excessive concentrations turning clear; effectively bleaching the water sample and the DPD reagent.
For swimming pools, a DPD reagent is commonly found in test kits designed to test oxidizers such as chlorine and bromine.
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