Blog Simple filter coffee recipe : 25 ppm General Hardness (as CaCO₃) from Calcium Chloride 15 ppm General Hardness (as CaCO₃) from Calcium Sulfate 10 ppm Carbonate Hardness from Baking Soda Making the Concentrate: For 1 liter of concentrate, mix: CaCl₂: 0.37 g CaSO₄: 0.26 g NaHCO₃: 0.17 g Using the Concentrate: For 0.5 L of brew water Add 50 mL of concentrate to 450 mL of pure water. Water calculator