A calibration standard in distilled waterCertified ValuesAlkalinity, Total (as CaCO3) . 1.5 mg/L Total hardness (as CaCO3) . 147.9 mg/l Ca . 42.8 mg/L K . 0.884 mg/L Cl. 105.5 mg/L Silica (as Si) . <0.03 mg/L Colour (Hazen units) . 1.5 Na. 119.3 mg/L D