Reagent
A reagent is a chemical used in a water test kit that reacts with the parameter being measured to produce a measurable colour change.
Definition
A reagent is a chemical used in a water test kit that reacts with the parameter being measured to produce a measurable colour change.
Typical Values: Shelf life: 2 years from manufacture date; replace annually for regular users
In Plain Language
Pool test kits contain multiple reagents, each targeting a specific water parameter. DPD-1 and DPD-3 reagents measure free and total chlorine. Phenol Red measures pH. Other reagents measure alkalinity, hardness, and CYA. Reagents have a shelf life (typically 2 years if stored correctly) and degrade when exposed to heat, humidity, light, or chemical vapour.
Why It Matters
Degraded reagents produce incorrect readings. Replacing reagents annually is essential for reliable test results.
Typical Values
Shelf life: 2 years from manufacture date; replace annually for regular users
Last reviewed: 2026-06-01