Why temperature changes everything
The Langelier Saturation Index drops as water cools. The same pH, alkalinity and calcium that read balanced at 88°F can read clearly aggressive at 52°F.
Aggressive water pulls calcium out of the nearest source — plaster, grout and tile joints. You will not see it in a week. You see it in spring as roughness, dull color or a gritty feel underfoot.
What to adjust as it cools
Let pH and alkalinity sit toward the upper end of their ranges instead of the summer middle. Do not chase calcium up overnight; small, measured corrections are safer.
Recalculate balance after each real cold front. A November reading does not hold for January.
How we handle it
Every visit logs water temperature with the readings, and balance is recalculated with that temperature before anything is added. Winter targets are shifted on purpose, not left on summer settings.