Pool in a heatwave: the right reflexes in high heat
Heat speeds everything up: algae grow faster, chlorine is used up faster, and water evaporates. In a heatwave, a few adjustments stop the water from turning in a matter of days.
In short
Above 28 °C, the water becomes an ideal ground for algae and bacteria, while chlorine degrades faster and evaporation lowers the level. The three reflexes: greatly extend filtration (up to 24/7), keep chlorine sufficient, and watch the water level so the pump does not lose prime.
Filter much more
The baseline rule — filtration time equal to the water temperature divided by two — already pushes the duration up as the water warms. Above 28 °C, continuous filtration is often needed: it is filtration, more than treatment, that stops the water from turning in the heat.
Chlorine and water level
Chlorine is consumed faster in heat and sun: watch it closely and make sure the stabiliser protects it (around 30 mg/L). Evaporation, meanwhile, lowers the level: keep it in the middle of the skimmers, or the pump may lose prime and run dry.
What to do, step by step
Extend the filtration
Raise the duration as the water warms, up to 24/7 in a full heatwave.
Watch the chlorine
Check it more often: it is used up fast. Make sure the stabiliser protects it from the sun.
Keep the water level up
Evaporation lowers the level: keep it in the middle of the skimmers so the pump does not lose prime.
Cover at night if you can
A cover limits evaporation and warming, and reduces product consumption.
Frequently asked questions
How long should I filter in a heatwave?
Far more than usual: above 28 °C, continuous filtration (24/7) is often needed to stop the water from turning.
Why does my chlorine drop in high heat?
Because heat and UV consume it faster. A stabiliser around 30 mg/L protects it; without it, it disappears within hours.
Should I swim less in a heatwave?
Not necessarily, but heavy use in high heat loads the water fast: strengthen filtration and watch the chlorine accordingly.