Cloudy From Sunscreen and Swimmers

How to tell this is your cause

• **The cloudiness correlates with use, not weather.** Clear on Friday, hazy on Sunday evening, after a full pool.
• **There is often foam**, particularly where the returns break the surface or in a corner.
• **There is a visible scum line** at the waterline, or the tile feels slightly greasy.
• **Free chlorine dropped sharply** over the weekend without any obvious other cause.
• **A clarifier helped a bit and not enough**, if you already tried a polymer one.

What each swimmer actually brings

Sunscreen is the largest contributor and the hardest to remove, because it is formulated specifically to resist washing off. On top of that: body oils, sweat, cosmetics, hair product, deodorant and lotion. None of it dissolves, all of it consumes chlorine, and most of it is far below the micron rating of a residential filter.

The chlorine demand is the part people underestimate. A busy afternoon can drop free chlorine measurably, which is why a party pool goes cloudy and under-sanitized at the same moment.

The fix, in order

1. **Test and restore free chlorine first.** The organic load has been consuming it. Use the dose tables for your volume.
2. **Shock the pool.** This is one of the genuine cases for a routine shock: you are oxidizing an organic load rather than killing algae. Cal-hypo suits it, and evening is the right time.
3. **Run the filter continuously for at least 24 hours.**
4. **Add a chitosan clarifier rather than a polymer one.** Chitosan binds oils specifically, which is the case polymers handle worst.
5. **Clean the waterline.** The scum line is oil that is out of the water column and will go back in the next time the level changes.
6. **Clean the filter afterwards.** Oil coats filter media and does not backwash off; a cartridge may need an enzyme soak or replacement.

Prevention, which works better than treatment here

• **A rinse before swimming removes a surprising amount** of what would otherwise end up in the water. It is the single most effective intervention and it costs nothing.
• **Apply sunscreen twenty minutes before swimming**, as most labels already advise, so it has bound to skin rather than washing straight off.
• **Fit a skimmer sock.** A few dollars of fine mesh over the skimmer basket removes far more fine organic debris than most people expect, and it does it before the pump.
• **Run the filter longer on days the pool was busy**, not the same hours as every other day.
• **Shock after a party, not three days later**, while the load is fresh and before it has fed anything.

Why a skimmer sock is in this list

It is the cheapest item on this site and one of the most effective. A skimmer basket catches leaves; everything smaller passes through it into the pump and then the filter. A fine-mesh sock over the basket intercepts hair, lotion residue, insects and grit before any of that happens.

The one caution is flow. Socks restrict as they load, so check them when you check the basket rather than weekly, and do not fit one to a pump already running at marginal flow.

The picks

Top pick - Oils and sunscreen

AquaDoc Natural Pool Clarifier, chitosan, 32 oz

Different chemistry to the rest of this page: chitosan binds oils, which is the cause polymer clarifiers handle worst.

The published figure

Chitosan-based clarifier, a shellfish-derived polymer

Chitosan is derived from crustacean shells and binds organic material — body oils, sunscreen, lotion — more readily than the synthetic polymers do.

That makes it the specific answer to a pool that goes cloudy after a busy weekend rather than after a storm, which is a distinction almost nobody makes on the shelf.

It is also the one to avoid if anyone using the pool has a shellfish allergy, for obvious reasons.

What it does well

• Binds oils and lotions better than synthetic polymer clarifiers
• Biodegradable active ingredient

What it costs you

• Shellfish-derived, which is a real consideration for some households
• Less effective than a polymer on mineral and dead-algae haze

Skip it if your cloudiness followed a storm or a shock rather than a pool party — the cause is mineral or dead algae and a polymer clarifier suits it better.

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Pick 2 - Sand filters

Clorox Pool&Spa Super Water Clarifier, 1 quart

A conventional polymer clarifier from the most widely stocked brand, which matters when the water is cloudy on a Saturday.

The published figure

Concentrated polymer clarifier, one quart

A clarifier is a coagulant: it makes fine particles clump until they are large enough for the filter to catch. That means it only works if the filter is running and clean, which is the step people skip before deciding the product failed.

Polymer clarifiers suit sand filters well, because sand catches particles down to roughly 20 microns and the clarifier's job is to lift the haze above that threshold.

Give it a full filter cycle. Clarifier is a 24 to 48 hour product, and re-dosing at hour six because nothing has happened is how people end up over-treating.

What it does well

• Stocked nearly everywhere, which is the whole point in an emergency
• Concentrated, so a quart treats several doses
• Works with the filter you already have rather than requiring vacuum-to-waste

What it costs you

• Needs a clean, running filter to do anything
• Slower than flocculant when the water is badly clouded

Skip it if your water is so cloudy you cannot see the bottom step. That is flocculant territory, not clarifier.

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Pick 3 - Catching what the net misses

Coopache Pool Skimmer Socks, 30-pack

A few dollars of fine mesh over the skimmer basket removes more fine debris than any chemical on this site.

The published figure

Fine-mesh elastic liners for the skimmer basket, 30 per pack

A skimmer basket catches leaves. Everything smaller goes through it and into the pump, then into the filter, where it is your filter's problem.

A sock over the basket takes pollen, hair, insects and grit out before any of that happens, and it is the single cheapest upgrade to a pool's water clarity.

They restrict flow as they load. Check them at the same time you check the basket, not weekly.

What it does well

• Removes the fine debris that otherwise loads the filter
• Costs less per season than a single bottle of clarifier
• Extends the interval between filter cleans

What it costs you

• Restricts flow noticeably once loaded, and needs checking often
• Disposable, so there is a small ongoing cost

Skip it if your pump already runs at marginal flow. A loaded sock will starve it.

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