Late winter — February and March
Water is cold, which pushes LSI negative and makes water aggressive toward plaster even at a 'good' pH. This is when quiet etching happens.
Live oaks begin dropping. Get ahead of the debris now and the spring green-up never starts.
Best window of the year for a drain to clean if cyanuric acid is high: mild temperatures, low sun, less risk to an empty shell.
Spring — April and May
Water crosses roughly 60°F and algae becomes possible again. Chlorine demand climbs before most owners think to raise it.
Raise run time, brush more, and get a filter clean in before the season loads it up.
Good time for a pool school refresher, while a mistake is still cheap to fix.
Summer — June through September
Peak everything: evaporation, bather load, sunlight destroying chlorine, and hard fill water pushing calcium and alkalinity up with every top-off.
Watch calcium hardness climb all summer from evaporation and refill. Scale on tile and salt cells starts here.
This is when cutting corners shows within days rather than weeks.
Fall — October and November
Main leaf drop. Baskets, cleaner bags, and netting matter more than chemistry this month, though the debris drives the chemistry too.
Water cools, demand drops, and run time can come down — but not before the trees are done.
Clean the filter after the drop, not during it.
Winter — December and January
Freeze readiness: know how your equipment protects itself, how to run the pump through a hard freeze, and where your shutoffs are.
Cold water is aggressive water. Calcium hardness and alkalinity need to be right, or winter quietly costs you surface.
Do not stop servicing the pool because nobody is swimming. Water does not take the winter off.
