Leaf season, and the three weeks that decide next April

Why leaves are worse than they look

A leaf on the surface is a tidiness problem. A leaf on the floor is three separate problems, and they compound.

It consumes chlorine. Organic material decomposing in the water is exactly what your sanitizer is there to deal with, and a floor covered in leaves can hold free chlorine below the CDC’s published minimum of at least 1 ppm — or 2 ppm with a stabilizer in use — no matter how diligently you dose.

It loads the filter. Breaking down leaves become fine particulate that goes straight into the cartridge, which is why autumn shortens the replacement interval that Intex already puts at roughly every two weeks in heavy use.

It stains the liner. Leaf tannin leaves brown patches exactly where the leaves sat, and they can persist. They are organic stains, so they respond to chlorine — our liner stains guide has the tablet test that distinguishes them from metal marks — but the easier answer is not letting them settle.

The autumn routine

The skimmer, which does the work while you are asleep

Most leaf fall happens overnight and on windy afternoons, which is precisely when nobody is standing beside the pool with a net. That makes the skimmer the primary defense in autumn rather than a supporting one.

Three things decide whether it does its job. The water level has to be at about the middle of the skimmer opening — too high and it stops skimming, too low and the pump draws air. The basket has to be empty, because a full basket throttles flow and produces exactly the symptoms of a failing pump. And the weir flap has to swing freely, because if it sticks open, everything the skimmer caught floats straight back out when the pump stops. Our skimmer guide covers all three.

It is also worth running the pump when leaves arrive rather than on a fixed overnight block. Two shorter daytime runs across the windy part of the day catch far more than one long run at 2am — our run-time guide covers scheduling.

The cover, used differently from summer

In summer a solar cover is about heat and evaporation. In autumn its most valuable property is that it is a lid: leaves land on it rather than in the water, and you lift them off with the cover rather than fishing them out.

Two cautions. Clear the cover before you pull it off, or you tip the whole load into the pool and turn a two-minute job into a vacuum session. And do not let water pool on top of it — a puddle on a cover is a still-water habitat sitting directly above your pool, which is the mosquito problem our pool bugs guide covers.

Deciding when to stop

There is a point where keeping the pool open through leaf fall costs more effort than the remaining swims are worth, and the honest signal is usually the daily skim becoming a chore rather than a habit.

Two things push in opposite directions. Closing early means fewer swims, and our cost per swim guide is clear that the denominator is where the value is. But closing while the water is still warm is the most expensive mistake in this hub, because a biologically active pool under a cover for five months is how people find a swamp in April — our cost of a bad close prices it and the green opening guide is what it looks like.

The rule that resolves it: close on water temperature, not on the calendar and not on leaf fall. Wait for consistently cold water, and use the leaf weeks before that to keep the pool clean rather than to decide the date.

If you take the pool down each autumn

Leaf season interacts with the take-down date in one specific way: vinyl folded in cold weather cracks along the folds, so there is a window where the water is cold enough to close and the air is still mild enough to fold the liner safely.

That window closes earlier than people expect, which argues for not leaving the take-down until the last leaf has fallen. Our take-down guide covers the sequence, and the lawn guide makes the same argument from the other direction: the grass under the pool needs growing season to recover, and October does not have any.

The one job to do before closing

Whatever date you pick, get every leaf out first. Organic material left in a pool over winter decomposes, consumes whatever chlorine is left, stains the liner where it settles and produces a sludge layer the filter cannot handle in spring.

A thorough skim, brush and vacuum on closing day is the same half hour you would spend on a normal week, and it is the difference between an opening that takes a morning and one that takes a fortnight. Our winterizing guide puts it in sequence.

If the leaf fall is heavy enough that this is an annual problem, the fix is a net rather than a routine. Our leaf net roundup covers sizing and mesh, and the yard test that decides whether it is worth buying at all.