Hanna Instruments Total Hardness Test Kit (0–800 mg/L CaCO3) 50 Tests (HI3890)

Hanna Instruments Total Hardness Test Kit (0–800 mg/L CaCO3) 50 Tests

The HI3890 is a genuine Hanna Instruments Pool Line chemical test kit designed to measure total water hardness as CaCO3 using a straightforward titrimetric method. It is ideal for pool owners and technicians who need to monitor calcium and magnesium levels to protect pool infrastructure and maintain balanced water. Each kit contains enough reagents for 50 individual tests.

How it works

The HI3890 uses an EDTA titration with a Calmagite colour indicator. Calcium and magnesium ions in the water sample form a complex with the Calmagite indicator, producing a red-coloured solution. As the EDTA reagent (hardness buffer) is added drop by drop, it progressively complexes the metal ions; once all ions are bound, the indicator is released and the solution turns blue — marking the clear, easy-to-read endpoint of the titration. The number of drops used directly determines the total hardness reading in mg/L CaCO3.

Why balanced hardness matters for pools

Water that is too hard encourages calcium and magnesium salt deposits to form on pool walls, fittings, and equipment. Water that is too soft can be corrosive, attacking surfaces and metalwork. Regular testing with the HI3890 helps pool professionals maintain the ideal hardness range, protecting both the pool structure and bather comfort.

What’s included

The kit ships complete and ready to use: one 30 mL dropper bottle of hardness buffer reagent (EDTA solution), one 10 mL dropper bottle of Calmagite indicator, and one 50 mL calibrated plastic beaker — everything needed to perform up to 50 tests straight out of the box. Replacement reagents are available separately when supplies run low.