Water-ID - DPD No. 4 Reagent Tablets for Active Oxygen/MPS – Pack of 250 - TbsPD4250

Water-ID – DPD No. 4 Reagent Tablets for Active Oxygen/MPS – Pack of 250

These photometer-grade DPD No. 4 tablets are the genuine Water-ID reagent for measuring Active Oxygen (MPS/persulfate) levels in pool and spa water using the Water-ID PoolLab 1.0 photometer. A pack of 250 individually blistered tablets provides an ample, long-lasting supply for regular professional or residential water testing.

What DPD No. 4 Measures & Why It Matters

DPD No. 4 is the standard reagent method for pools disinfected with persulfate-based Active Oxygen products, delivering readings across the 0.0–30.0 mg/l (ppm) range. Active Oxygen is a popular chlorine-free disinfection alternative, especially in Northern Europe, but its efficacy is short-lived — regular testing ensures your sanitiser level stays within the effective zone and bathers are protected. DPD No. 4 can also be used to test for total bromine in bromine-treated spas, since both free and combined bromine are disinfectant and together indicate overall sanitisation capacity.

Compatibility

These tablets are calibrated exclusively for use with the Water-ID PoolLab 1.0 photometer. They are not intended for use with colorimetric comparator kits or third-party photometers. Always use photometer-grade tablets — never substitute rapid or visual-grade tablets — to ensure accurate readings from your device.

How to Use

Fill the PoolLab 1.0 cuvette with a fresh pool water sample, add one DPD No. 4 tablet without touching it directly, allow it to dissolve, and initiate the Active Oxygen measurement on the device. Tablets are supplied in aluminium push-through blisters (10 per blister) to protect them from moisture and contamination until the moment of use. Replace tablets if the 2-year shelf life has been exceeded or if discolouration is visible.