• Determine the water hardness easily and reliably with this test kit. • Interpret the water according to German hardness or ppm to know if it is soft, medium, or hard. • Check the performance of your water filter and determine if it needs replacement. • Apply in osmosis systems, softening, carbon filters, espresso machines, washing machines, dishwashers, aquariums, ponds, and pools. • Add 5 ml of test liquid to the sample tube and drops until the color changes from red to blue. • 1 drop equals 1 German hardness (17.8 ppm). • If the liquid turns blue immediately, the hardness is approximately 0 dH. • Kit contents: 1 15 ml titration solution, 1 sample tube, 1 pipette. • More accurate method than test strips. • Water can fluctuate up to 3 degrees of hardness in a day.