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Pool Line Quick Total Hardness Chemical Test Kit - HI38904

HI38904 Pool Line Quick Total Hardness (TH) Chemical Test Kit is a basic test for the measurement of total hardness, as CaCO3, in swimming pools, hot tubs, and spas.

  • Pre-made reagents for ease of use
  • All reagents marked with expiration date and lot number for traceability
  • Manual titration performed with color indicator with a range to 800 ppm


Water hardness, especially as calcium, is an important parameter along with pH and alkalinity in maintaining the water chemistry of a swimming pool or hot tub. Water hardness includes both calcium and magnesium ions that are found naturally in water and will vary in concentration based on region and water source. Water sources include lakes, rivers, streams, and groundwater (wells) with groundwater typically being the highest since minerals are picked up by rainwater as it percolates through the soil. For examples in areas with a lot of limestone the groundwater will be high in calcium carbonate.

Hardness is an important measurement since if the levels are high the calcium carbonate is likely to precipitate, especially as the pH increases, will lead to cloudy water, clogged filters, and heater inefficiency. If hardness is low then the pool water will attack with calcium carbonate (lime) that is used in grout and concrete leading to pitting and etching.

The HI38904 is a titration-based chemical test kit that determines the total hardness concentration within the 0 to 800 ppm (mg/L) range. The HI38904 is supplied with all of the necessary reagents and equipment to perform the analysis for total hardness.

  • Complete setup
    • All required materials are included with the test kit, such as the sample beaker and reagent dropper bottle.
  • High resolution
    • Readings from 0 to 800 ppm (mg/L) are determined with a 10 ppm (mg/L) resolution.

Hardness Level ℉H °dH ppm (mg/L)
Very Soft 0 – 7 0 – 4 0 – 70
Soft 7 – 15 4 – 8 70 – 150
Slightly Hard 15 – 25 8 – 14 150 – 250
Medium Hard 25-32 14 – 18 250 – 320
Hard 32 – 42 18 – 23 320 – 420
Very Hard >42 >23 >420

1 TH = 1 ℉H = 0.562 °dH = 0.2 meq/L = 10 ppm (mg/L) CaCO3

Additional information

Weight 0.23 kg



SKU HI38904
Name Pool Line Quick Total Hardness Chemical Test Kit – HI38904
Hardness, Total Range 0 to 80 TH
0 to 800 ppm (mg/L) CaCO3
Hardness, Total Resolution 1 TH
10 ppm (mg/L) CaCO3
Hardness, Total Method Drop-count titration

Ordering Info

HI38904 Hardness Chemical Test Kit is supplied with 30 mL hardness buffer, 10 mL calmagite indicator, and 50 mL plastic beaker with cap.


Pool Line Quick Total Hardness Chemical Test Kit – HI38904