What does the filtration time depend on and what filtration time is necessary for my pool? The number of bathers, the volume of water, the type of water maintenance treatment, etc. Many factors influence the quality of the water, but also the duration of filtration.
However, the most influential element on filtration time is the water temperature. The higher the water temperature, the more the pond water will favor the development of bacteria and green algae.
How to know the filtration time of swimming pool water?
Easy to remember, the water filtration time is calculated according to the following formula:
Filtration time = Water temperature / 2
Example: 25/2 = 12.5 or with a water temperature of 25°Cyou will need to filter at least your pool water pending 12 h.
This formula is valid mainly from spring to autumn. In winter, when temperatures drop below 10 degrees, bacteria, fungi, algae and microorganisms will no longer be able to grow.

Here is a small summary table of the filtration time:
| Water temperature | Minimum filtration time |
| T° < 10°C | – |
| 10°C < T° < 12°C | 4 hours |
| 12°C < T° < 16°C | 6 hours |
| 16°C < T° < 24°C | 8 hours |
| 24°C < T° < 27°C | 12 hours |
| 27°C < T° < 30°C | 8pm |
| T° > 30°C | 24 hours |
Now that you have an idea of the filtration time needed for your pond water, there are still a few small details to add to this calculation. As mentioned earlier in the article, some factors will affect the filtration time.
Attendance and swimmers
The turnout and number of swimmers in your pool will play a role in the development of microorganisms during the summer period. Obviously, for a family swimming pool or for an exceptional occasion in which you will welcome many guests, just add 1 or 2 hours more to the usual filtration time.
Small tip: simple accessories to adapt such as a foot bath or an outdoor shower can reduce the elements of dirt in the pool.
Read our article: Sand, zeolite or filter glass, what to choose for the filtration of my pool?
Pool water treatment
The type of cleaning products must also be taken into account. Swimming pool water treated with similar productsactive oxygen or PHMBwill require an increase in filtration time.
In reality, these maintenance products have none lasting effects. Limited filtration will have less effective effects on water quality. Remember to use the most suitable treatment for your pool and regularly clean the pool (bottom, walls, etc.) and the filtration system.
Your swimming pool filtration system
Equipment for your filtration system also plays an important role.
At the time of purchase the swimming pool is sold with a filtration system (a pump and a filter) adapted to the size and volume of the pool water.However, if this is not the case, you will need to take into account the under or over sizing of your filtration equipment for the duration of your water filtration.
If the equipment is undersized and the filtration system is weak, it will be necessary to extend the filtration time and, conversely, reduce the filtration time if the equipment is oversized.
For economic and speed reasons it is believed that swimming pool water should renewable in 4 hours. Therefore, to calculate the filtration flow rate and know the equipment suitable for a swimming pool, it is necessary to divide the volume of the pool water by 4.
Filtration flow rate (m3/h) = volume of pool water (m3) / 4 (hours)
For an even more exact calculation it is necessary to integrate it into the formula a coefficient that takes into account pressure loss, surrounding pollution or the state of the filter.
The calculation will be as follows with the clogging coefficient:
Filtration flow (m3/h) = (pool water volume (m3) /4 (hours) x 1.20
What time of day should you filter your pool?
While many pool owners are tempted to filter pool water overnight for economic reasons, The recommended time for water filtration is during the day.
In fact, bacteria and microorganisms are more active during the day, when temperatures are high and in the presence of swimmers, so it is at this time that it is most necessary to filter the water.
If you plan to filter at night to save electricity, you may end up increasing your water treatment products later. Therefore increasing water maintenance costs.
We recommend splitting your filtering sessions into multiple times.
For example, 2-3 filtering sessions during the day and one filtration session while swimming and another, for example, when treating pool water.
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