What to Do With Your Pool After Rain in Los Angeles

Los Angeles gets its rain in a handful of heavy days rather than steady drizzle, and that is exactly what makes it hard on a pool. A single storm can undo a month of balanced water: the chlorine is diluted, the pH drops, the baskets fill, and the level rises over the skimmer so the surface stops being cleaned at all. Left alone through a wet week, that is how a clear pool turns green by the time anyone looks at it again.

The work itself takes under an hour. The order matters more than the effort.

Do This First, in This Order

1. Clear the surface and the baskets. Leaves left to sit turn into phosphates, and phosphates feed algae. Empty the skimmer basket and the pump basket, not just one of them.
2. Bring the water level back down. The correct level is halfway up the skimmer opening. Over the top of it, the skimmer draws nothing and the surface debris stays where it is.
3. Test before you add anything. Free chlorine, pH, total alkalinity. Rainwater in the LA basin is acidic and lands around pH 5 to 5.5, so expect both pH and alkalinity to have fallen.
4. Fix alkalinity first, then pH. In that order, because alkalinity moves pH with it. Target 80–120 ppm alkalinity, then 7.4–7.6 pH.
5. Shock, at dusk. After a normal storm a double dose is enough: about 2 lb of cal-hypo per 10,000 gallons. Sunlight burns off shock added during the day, which is why it goes in after sunset.
6. Run the pump 12 to 24 hours and clean the filter after. The filter is about to catch everything the storm brought in. Watch the pressure: 8–10 psi above clean means rinse or backwash it.

Why the First Rain of the Season Is the Worst

Rain is not clean water here. Between May and November nothing washes the air or the roofs, so the first real storm carries down everything that has been settling since spring: road dust, smog particulates, pollen, roof grit, and in a fire year, ash from the hills. All of it lands in the pool at once.

That is why the first storm of the season usually needs a full shock and a filter clean, while the third or fourth one in February often needs only a test and a small correction. If your water goes cloudy and stays cloudy after that first rain, phosphates are the usual reason — worth testing for, because no amount of chlorine fixes them.

The Overflow: Do Not Send It to the Street

When the pool is over the coping, the instinct is to open a valve and let it run down the driveway. Do not. Pool water is chlorinated, and most cities we work in prohibit it going into a storm drain — storm drains in Los Angeles County run to the ocean without treatment, and the fines are real.

How Long Cloudy Water Takes to Clear

• Slightly hazy after one storm: 24 hours with the filter running and the chemistry corrected.
• Properly cloudy, bottom visible but soft-focus: 2 to 3 days, and it needs the filter cleaned partway through.
• Cloudy and still cloudy after three days: something else is wrong — a filter that needs more than a rinse, phosphates, or algae that has already started. At that point adding more chlorine is just spending money.
• Green: past the rain problem and into a different job — see how to clean a green pool.

Before the Next Storm

Twenty minutes of preparation saves the hour afterwards. Before a storm is forecast:

• empty the baskets, so they start the storm with room in them;
• lower the water an inch or two if the pool is already near the top of the skimmer;
• test and correct the chemistry, so what gets diluted is water that was balanced to begin with;
• leave the cover off unless it is a solid safety cover — a mesh or floating cover collects debris and sinks;
• put loose deck furniture and the pole and net away, so they do not end up in the water.

What not to do: shut the pump off for the duration. Circulation is what keeps the diluted chlorine spread through the pool, and a pump that sits idle through three wet days is how green water starts.

When to Call Someone

Through the wet months we get the same three calls. Water that has been cloudy for more than three days. Water that went green while nobody was swimming and nobody was looking. And a pump that will not restart after a storm — usually a tripped GFCI or water where it should not be, occasionally a motor that has taken in water and is finished.

If any of those is your week, send us a photo of the water or call (818) 740-6099. Diagnosis on equipment is $0 in our service area, and a storm clean-up is a fixed price once we have seen what is in the pool.