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Total Hardness Test Kit - HI38033

The HI38033 is a chemical test kit that measures total hardness as CaCO3 by titration with EDTA. The HI38033 is supplied complete with all of the reagents and equipment necessary to perform approximately 100 tests.

  • Pre-made reagents for ease of use
  • All reagents marked with expiration date and lot number for traceability
  • Manual titration performed with color indicator


The HI38033 is a titration-based chemical test kit that determines the total hardness concentration within the 0 to 30 grains per gallon (gpg) range. The HI38033 is supplied with all of the necessary reagents and equipment to perform the analysis. The test kit contains enough reagents for perform approximately 100 tests. The hardness level as gpg calcium carbonate (CaCO3) is determined by an EDTA (ethylene-diamine-tetraacetic acid) titration. The solution is first adjusted to a pH of 10 using a buffer solution. The indicator chelates with metal ions such as magnesium or calcium to form a red colored complex. As EDTA is added, metal ions complex with it. After all the free metal ions have been complexed, an excess EDTA removes the metal ions complexed with the indicator to form a blue colored solution. This color change from red to blue is the endpoint of the titration.

Features at-a-glance

  • Complete setup
    • All required materials are included with the test kit, such as the sample beaker, plastic pipette, and reagent bottles.
  • High resolution
    • Readings from 0 to 30 gpg are determined to 1 gpg resolution.
  • Replacement reagents available
    • There is no need to buy a new kit when reagents are exhausted. The HI38033-100 reagent set can be ordered to replace the reagents supplied with the kit. This reagent set comes with 1 (30 mL) dropper bottle of buffer solution, 1 (10 mL) dropper bottle of Calmagite indicator, and 2 (75 mL) bottles of HI38033-0 EDTA solution.

Significance of Use

Water hardness has traditionally been defined as the capacity of water to precipitate soap. The ionic species in the water causing the precipitation was later found to be primarily calcium and magnesium. Thus, water hardness is actually a quantitative measure of these ions in the water. It is also now known that certain other ion species, such as iron, zinc, and manganese contribute to the overall water hardness. The measure and subsequent control of water hardness is essential to prevent scaling and clogging in water pipes.

Additional information

Weight 0.43 kg



SKU HI38033
Name Total Hardness Test Kit – HI38033
Hardness, Total Measurement Type titration
Hardness, Total Range 0 to 30 gpg CaCO₃
Hardness, Total Resolution 1 gpg
Hardness, Total Method EDTA
Hardness, Total Number of Tests 100
Weight 457 g (16.1 oz)
Dimensions 235x175x115 mm (9.2×6.9×4.5 in.)

Ordering Info

HI38033 test kit comes with 30 mL buffer solution, 10 mL calmagite indicator, 75 mL EDTA solution (2), 20 mL plastic beaker with cap, and 1 mL plastic pipette.


Total Hardness Test Kit – HI38033