Water-ID - DPD No. 3 Reagent Tablets for Total & Combined Chlorine – 250 Pack - TbsPD3250

Water-ID – DPD No. 3 Reagent Tablets for Total & Combined Chlorine – 250 Pack

These genuine Water-ID DPD No. 3 photometer-grade reagent tablets are designed for accurate measurement of total chlorine and combined chlorine (chloramines) in pool and spa water. Used in sequence after a DPD No. 1 free-chlorine reading, each tablet reveals the total chlorine concentration — and the difference between the two readings gives you combined chlorine directly. The 250-tablet pack is ideal for busy pool professionals and high-frequency testers who need a reliable, long-lasting supply.

Why Total & Combined Chlorine Matter

Combined chlorine — the chloramine fraction of total chlorine — is largely ineffective as a sanitiser and is responsible for the characteristic pool odour and the eye and mucous membrane irritation swimmers experience. Monitoring combined chlorine allows you to determine when breakpoint shock treatment is needed, keeping water safe, comfortable, and compliant. With the DPD method, chlorine measurements are distinguished according to DIN EN 7393, giving you a complete picture: free chlorine, combined chlorine, and total chlorine.

How to Use

First take a free-chlorine reading using a DPD No. 1 tablet — do not empty the cuvette. Then add one DPD No. 3 tablet to the same sample and mix; the photometer now reads total chlorine. Subtract the free-chlorine value to calculate combined chlorine. Thoroughly clean the cuvette, cap, and stirring rod after every DPD No. 3 measurement, as trace residues can interfere with subsequent DPD No. 1 readings. Always use the light-protection cover and ensure no air bubbles are present during measurement.

Compatibility & Storage

These tablets are formulated exclusively for use with the Water-ID PoolLab 1.0 photometer. Each tablet is individually sealed in an aluminium push-through blister pack (10 tablets per blister) to protect against moisture and contamination. Store in a cool, dry place at 15–25 °C to maintain accuracy and support the full 2-year shelf life.