... tests/box Fast, Easy-to-Use, Accurate Low hardness of water Test Kit1. SpecificationName: Low hardness of water Test KitModel: LH-P08Type: quantitaitveColor reaction ... I, sway the flask, if the liquid become blue, the hardness of water is below 0.4mg/L, or please go ... 1mL is not enough, record the volume V.5. The hardness of the testing liquid =V*20 (mg/L, calculated as ...