Winter Pool Care in Los Angeles: What Changes, What Doesn't

Search for winter pool care and you get pages about winterizing: lowering the water, blowing out the lines, putting a cover on until spring. That is for pools that freeze solid. A Los Angeles pool stays open all year, and doing the closing routine to it creates problems it never had.

Do not drain it

The one winter mistake that costs real money is lowering the water or emptying the pool. Plaster is meant to sit under water. An empty shell can crack, and after a wet week the soil around it can push it up out of the ground. If a repair needs the water out, a pro plans it around the weather. See the pool after rain page for what to do when the water level rises on its own.

What actually changes when the water cools

• Chlorine lasts longer. Low sun and cool water burn it off slowly, so a dose that vanished in July can hold for days. Test before you add: the readings are on the pool chemistry page, and pouring by habit is how a winter pool ends up over-chlorinated.
• Algae slows down and does not stop. A pool in the low 60s grows it far more slowly than in August, but rain, leaves and low chlorine still start it. The green pool page covers the cleanup if it gets ahead of you.
• The pump can run fewer hours. Many LA pools do well on 6 to 8 hours a day in winter. Treat that as a starting point and watch the water, because the right number depends on the pump and on how many leaves fall in.
• A salt cell may switch itself off. Most stop producing chlorine when the water falls to about the high fifties. The saltwater maintenance page explains how to cover that gap by hand.

What does not change is testing. Cold water hides problems for a few days and then shows all of them at once, usually right after the first big rain.

The few nights that freeze

Most of the basin never reaches 32°F. The foothills do, a handful of nights a winter. Water that is moving freezes later than water that sits, so on a night with a forecast low near freezing the pump should run through the night, and an automatic freeze-protection setting on the control panel does that for you. On plenty of pools it was never switched on; our La Crescenta page has more on it for foothill owners. Check the setting in November, not on the cold night.

Leaves and storms are the real winter work

Sycamores and oaks keep dropping into December, and the first storm brings down what was left on the branches. A basket full of wet leaves slows the pump, and leaves left to sit on the floor of a plaster pool can leave brown stains that take chemistry to remove. Empty the skimmer basket more often than you do in summer, and net the surface before rain, not after.

If the filter is clogging faster than usual, the filter cleaning page covers what a cleaning involves and what it costs.

If you swim in winter

A heater is the one piece of equipment that works harder in winter, and it is the one most likely to be found broken the first cold weekend. Start it for a few minutes in November, before you need it. A heater that will not light or trips out is a job for the heater repair page. A pool cover keeps heat in overnight, but it also hides a dirty pool, so lift it and look at the water once a week.

A winter checklist

1. November: cut the pump schedule, switch on freeze protection, fire up the heater.
2. Weekly: test chlorine, pH and alkalinity, empty the baskets, net the surface.
3. Before every storm: clear the surface and check the chlorine, so the rain meets a pool that is ready.
4. After every storm: brush the walls, retest, and look at the water level.
5. Before you travel: see below.

Leaving for the holidays

Cool water forgives a missed week better than July does. What it does not forgive is a storm landing in the middle of that week. Before you go, test and bring chlorine to the middle of its range, empty the baskets, net everything off the top and check the pump schedule and freeze setting. For a trip longer than a week, ask someone to look at it, because a pool that turns green while you are away takes longer to clear than the trip did.

What winter service costs

Doing it yourself costs chemicals and time. Weekly service starts at $159 a month with standard chemicals included, as the price list shows, and the weekly maintenance page says the visit is the same list in January as in July: what changes is the pump timer and the leaf work.

Want someone else to watch the forecast? Send us the pool size and your last readings, or call (818) 740-6099.