Why Does My Swimming Pool Turn Green? (And How to Prevent It)

It can happen in just a few days…

Green Pool

One of the most common calls I receive during the summer is from concerned villa owners asking why their beautiful blue swimming pool has suddenly turned green.

The answer is usually simple: algae.

In the South of France, our combination of intense sunshine, warm temperatures, pollen, leaves and occasional summer storms creates the perfect environment for algae to grow if a pool isn’t monitored carefully.

Maintained Blue Pool

Unmaintained Green Pool

“The difference between these two pools wasn’t age or luck—it was regular monitoring and early intervention.”

Why pools turn green

A swimming pool doesn’t become green overnight. It begins with tiny algae spores that are always present in the environment.

They multiply when conditions are right, particularly if:

• Chlorine levels fall too low.

• The pH becomes unbalanced.

• The filtration system isn’t running long enough.

• Leaves and organic debris are left in the water.

• The pool isn’t checked regularly during hot weather.

Once algae establish themselves, the water quickly loses its sparkle before eventually becoming cloudy and green.

Why prevention is better than cure

Restoring a green pool can involve:

• Shock chlorination

• Vacuuming and brushing

• Cleaning filters

• Additional chemicals

• Several days before the pool is clear again

For holiday villas, this can mean disappointed guests and emergency call-outs at exactly the wrong time.

Regular inspections usually identify small issues before they become expensive ones.

How Aurelia helps

At Aurelia Villa & Project Management, we don’t replace your pool maintenance company—we work alongside them.

During our regular property inspections we look for the early warning signs:

• Water clarity changing

• Falling water levels

• Debris building up

• Equipment problems

• Unusual chemical readings (where appropriate)

If we spot an issue, we can arrange prompt action before it affects your guests or your investment.

A little prevention goes a long way

A swimming pool is often the centrepiece of a holiday villa. Keeping it crystal clear isn’t just about appearance—it’s about protecting your investment and ensuring every guest arrives to exactly the experience they were expecting.

If your property is empty for periods during the summer, regular inspections can make all the difference.