TM   5-6630-215-12 Table 2-4. Conversion Factors Calcium Hardness - (Calcium Carbonate - CaCO₃, Calcium Oxide - CaO) Units of Measure mg/lCaCO₃ English gr/gal. CaCO₃ USgr/gal.CaCO₃ Fr.p/100,000 CaCO₃ Ger.p/100,000 CaO mg/l g/lCaO lb/cu  ft  CaCO₃ Nitrogen mg/1 CaCO₃ 1.0 14.3 17.1 10.0 17.9 50.0 1,790.0 16,100.0 British gr/gal. Imperial) CaCO₃ 0.07 1.0 1.2 0.7 1.25 3.5 125.0 1,123.0 American gr/gal. (US) CaCO₃ 0.058 0.83 1.0 0.58 1.04 2.9 104.2 935.0 French parts/ 100,000 CaCO₃ 0.1 1.43 1.72 1.0 1.79 5.0 179.0 1,610.0 Nitrite (NO₂) = Nitrogen (N) x 3.28 Nitrate (NO₃) = Nitrogen (N) x 4.42 Ammonia (NH₃) = Nitrogen (N) x 1.22 Ammonium  (NH₄) = Nitrogen (N) x 1.29 Phosphate Phosphorus  (P)  =  Phosphate  (PO₄) x 0.326 Phosphorus  Pentoxide  (P₂O₅) = Phosphate (PO₄) x 0.75 WEIGHTS/VOLUME CONSTANTS (FROM - TO, MULTIPLY BY) German parts/ 100,000 CaO 0.056 0.8 0.96 0.56 1.0 2.8 100.0 300.0 mg/l 0.02 0.286 0.343 0.2 0.358 1.0 35.8 321.0 g/l CaO 5.6x10^-4 8.0x10^-3 9.66x10^-3 5.6x10^-3 1.0x10^-2 2.8x10^-2 1.0 9.0 lb/ cu ft CaCO₃ 6.23x10^-5 8.91x10^-4 1.07x10^-3 6.23x10^-4 1.12x10^-3 3.11x10^-3 0.112 1.0 1 TROY LB - 0.373 KG 1 GRAM - 0.038 AVOIR. OZ. 1 U.S. FLUID OZ. - 29.573 ML 1 GRAM - 18.432 GRAINS 1 AVOIR. LB - 0.484 KG 1 GRAM - 0.032 TROY OZ. 1 BRIT. FLUID OZ. - 28.412 ML  1 KG. - 2.205 AVOIR. LB TEMPERATURE (CELSIUS/FAHRENHEIT) [(KELVIN °K = °C + 273°)] INCHES - CENTIMETERS 2-13