When testing water chemistry, keep in mind that the units in which the measurements are given can easily be converted into other units. For example, when testing alkalinity some tests give their readings in parts per million (or ppm). If you are uncomfortable or unfamiliar with this unit, ppm can be easily changed to mg/L just by swapping the units since 1 ppm = 1 mg/L. Additionally, both of these can easily be converted to degrees of carbonate hardness (dKH) since 1 dKH = 17.848 mg/L CaCO. A 200 ppm (or mg/L) CaCO3 sample equals approximately 11.2 dKH.