Water-ID - DPD No. 4 Reagent Tablets for Active Oxygen – Pack of 500 - TbsPD4500

Water-ID – DPD No. 4 Reagent Tablets for Active Oxygen – Pack of 500

These genuine Water-ID DPD No. 4 photometer-grade tablets are designed to measure Active Oxygen (persulfate-based disinfectant) in pool and spa water, covering a range of 0.0–30.0 mg/l (ppm). Supplied in a bulk pack of 500 tablets, they are the ideal consumable for pool professionals and active owners who test regularly with the Water-ID PoolLab 1.0 photometer.

Why Test Active Oxygen?

Active oxygen is a popular chlorine-free disinfection method, particularly in northern Europe. Keeping persulfate-based active oxygen within the correct target range ensures effective sanitation without over- or under-dosing — both of which can compromise water hygiene and swimmer comfort. The DPD No. 4 method is the recognised standard for persulfate-based systems; note that if chlorine and active oxygen are used simultaneously, results may reflect the combined reading of both disinfectants rather than active oxygen alone.

Photometer-Grade Quality

Every tablet is produced, blistered, and packaged in Germany to photometer-grade standards, ensuring precise colorimetric reactions and repeatable, reliable readings every time. The aluminium push-through blister packaging (10 tablets per blister) protects each tablet from moisture and contamination right up to the moment of use. With a shelf life of 2 years, the 500-tablet pack offers excellent value for high-frequency testing sites.

How to Use

Fill the PoolLab 1.0 cuvette with the water sample, perform the ZERO calibration step with clean water, then add one DPD No. 4 tablet directly into the cuvette — handle tablets without touching them to avoid contamination. Place the light-protection cover and confirm the measurement on the device. Always use photometer-grade tablets; do not substitute rapid or colorimetric comparator tablets, as these will produce inaccurate readings in the photometer.