Pool filtration time: How many hours a day should you filter your pool?

The time required to filter swimming pool water is influenced by several factors. That being said, it remains relatively simple to calculate the daily filtration duration for your pool water. You simply need to carefully consider a few elements.

Water temperature and the filtration cycle

This is the most crucial element. Indeed, the filtration duration will vary according to the water temperature, and therefore the seasons. A simple formula allows you to determine the required filtration time based on the water temperature: you must divide the temperature in °C by two. The importance of water temperature lies in the fact that heat—meaning a temperature above 10°C—promotes the proliferation of bacteria and algae. In other words, the warmer the water, the longer the filtration duration must be.

The filtration cycle is another factor that helps estimate filtration duration, but it requires a slightly more complex calculation. However, this calculation is superfluous if the pump was correctly set during installation. If you prefer to stick to the filtration cycle, the calculation consists of: dividing the pool water volume by the pump flow rate. This calculation should provide a result equivalent to that of the water temperature.

It should also be noted that if the filtration time is relatively long, it is possible to divide it into two or three filtration cycles.

Other factors to consider

Timing of the filtration cycle

The moment you choose to filter the water is a factor to take into account. It is essential to emphasize that filtering pool water during the night is discouraged, even if energy costs are lower at certain times of the night. Indeed, the proliferation of bacteria mainly occurs in the presence of sunlight, during photosynthesis. At night, since this phenomenon does not take place, the water will not be filtered optimally.

Filtration products used

This is a factor to consider, as various pool treatment products do not offer the same results. For example, a treatment with active oxygen or PHMB requires a longer filtration duration because they do not have a persistent effect. In contrast, the filtration time for chlorine or bromine treatments corresponds exactly to the time calculated based on temperature or the filtration cycle.

The number of swimmers

The more swimmers there are, the longer the water filtration will be, as the number of bacteria will then be much higher. Public pools, for example, must run their filtration cycle continuously to guarantee the cleanliness of the water. For family pools, where the number of bathers is limited, programmed filtration cycles or those obtained through different calculation methods will be more than sufficient.

Here is a summary table for normal use in a private setting for a standard swimming pool:

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