Calculate the maximum addition (as mg/L or ppm) of calcium hydroxide required. Under normal circumstances the calculated amount should allow to precipitate all alkalinity assuming sufficient calcium is present in the water.
the starting water profile.
the concentration of calcium hydroxide as mg/L.
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Lime softening water treatment. http://www.braukaiser.com/wiki/index.php/Alkalinity_reduction_with_slaked_lime
TLDR;
Carbonic acid reacts with Calcium hydroxide to form Calcium carbonate which precipitates: H₂CO₃ + Ca(OH)₂ ⟶ 2 H₂O + CaCO₃↓
Bicarbonate reacts with Calcium Hydroxide and existing Calcium also to form Calcium carbonate which precipitates: 2 HCO₃ + Ca(OH)₂ + Ca ⟶ 2 H₂O + 2 CaCO₃↓
If water is Calcium deficient bicarbonates cannot be removed, since the remaining OH group reacts with Carbon dioxide to (re-)form bicarbonate: HCO₃ + Ca(OH)₂ + CO₂ ⟶ H₂O + CaCO₃↓ + HCO₃