Common pool problems and how to fix them

First things first: test

Almost every problem becomes clear once you test pH, chlorine, alkalinity and hardness. Good test strips give you a first idea. Always adjust the pH before any treatment, because with the wrong pH chlorine does not work properly.

If you prefer a more precise reading, this digital pH and chlorine meter is one we recommend on Amazon, or ask for one at a pool shop.

Green water or algae

• Cause: low chlorine, high pH, poor filtration or built-up cyanuric acid.
• What to do: brush the walls and floor, lower the pH, shock-chlorinate and run the filter continuously until the water clears.
• If it keeps coming back, see our guide on high cyanuric acid.

For brushing, a good brush or a brush and telescopic pole kit saves effort. For treatment, here are the shock chlorine, the pH reducer and an algaecide as support. Everything we recommend is on Amazon, or you can find it at any pool shop.

Cloudy or milky water

• Cause: dirty or undersized filter, lots of suspended dirt or unbalanced alkalinity.
• What to do: clean the filter, extend the filtration hours and use a flocculant so the dirt sinks to the bottom and can be vacuumed up.

To make the dirt sink to the bottom, use this flocculant we recommend on Amazon. If you would rather not clean by hand, a pool cleaning robot does the job; you can also ask for them at a pool shop.

Strong chlorine smell and irritated eyes

It is not usually too much chlorine, but combined chlorine. Adjust the pH and shock-chlorinate to get rid of it.

Foam on the surface

It usually comes from sun creams, cleaning products or some algaecides. Skim off the foam, run the filter and replace part of the water if it persists.

Stains and limescale

Limescale appears with high hardness or high pH. Keep the pH stable and check the hardness. If the value is very high, the solution is to dilute with fresh water.

When the water can't be saved

If the water has been building up stabiliser, salts and sediment for years, sometimes the cheapest and simplest option is to drain and refill. We can help with pool filling by tanker truck.

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Frequently asked questions

Why does the water turn green even though I add chlorine?

The most common causes are high pH or too much cyanuric acid, which leave the chlorine ineffective.

How often should I test the water?

In season, at least once a week, and always after heavy rain, heavy use or high temperatures.

When is it worth draining and refilling?

When the values are still out of control after correcting them, especially if the stabiliser or hardness is very high.

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