Additional Details ------------------------------ Product description: WaterWorks 481108 Total Hardness test strips test calcium levels from 0 to 1,000 ppm with a three-second test time. These total hardness water quality test strips evaluate calcium levels in residential, industrial, or educational applications. Each strip tests for total hardness from 0 to 1,000 ppm (parts per million) with sensitivity indicators at 0, 40, 80, 120, 180, 250, 425, and 1000 ppm (mg/L) or 0, 2, 5, 7, 11, 15, 25, and 58 gpg (grams per gallon). The three-second test time provides immediate results. Water quality test strips are typically used to analyze water quality in pools, aquariums, homes, industrial processes, educational experiments, and for homeland security applications. Industrial Test Systems manufactures water quality testing equipment for water treatment, food and beverage, pool What's in the Box? -WaterWorks 481108 Total Hardness Test Strips (30) -Color chart