The swimming pool pump : functioning how to choose it ?

No beautiful pure water in its private bathing area without the adequate pump. Power, flow… it is not always easy to choose this most important element of the swimming pool filtration system. So in order not to buy at random from the wide range currently on offer, you can take a look at the following advice, knowing that it is however essential to refer to your swimming pool specialist to choose the ideal pump since it depends on the characteristics of the swimming pool.

Purpose of the swimming pool pump

Fundamental element of hydraulic circuit of which it is the motor, the swimming pool pump feeds the pool filter so that all impurities can be removed. It is therefore essential for filtering the water and allowing users of the pool to enjoy the pleasures of swimming without fear. In addition, because it causes water movement (weak current), it promotes homogeneous dispersion of treatment products essential to maintain the perfect chemical balance of pool water. Note that the latter should absolutely not stagnate, thanks to the pump it never remains inert.

It must work perfectly since it holds the major role of the entire filtration system. In the event of a breakdown, the circulation of the pool water can no longer be carried out. Impurities accumulate, the quality of the water deteriorates: the swimming pool becomes unusable.

Operation of a swimming pool pump

The pool pump works a little like a lung except that it sucks up water: at the bottom of the pool via the broom sockets and the drain, and on the surface via the skimmers because it is through these different points that the water containing impurities arrives in the pool. It then passes through the filter where it is cleared of dirt.

Then, propelled by the pump, it returns clean to the pool, passing through the discharge nozzles and possibly through the heating device depending on the type of pool equipment.

Care must therefore be taken that the circuit that is still functional, not clogged, in perfect condition, and that its various elements are not dilapidated. Because it is a closed circuitit is also necessary to check that there is no air pocket disturbing it, which may be the case if there is air in the pump or in the pipes of the hydraulic circuit.

Selection criteria of the pump for the swimming pool

To have a efficient hydraulic circuitand therefore benefit from a pure waterit is essential to choose a pump perfectly adapted to the volume of the pool. If it is useless to opt for an ultra-powerful model in a small pool, buying a low-power pump is a mistake of choice if you have a large pool. Indeed, a pump of insufficient power will not allow the filtration work to be effective. Similarly, as the suction will be too weak, broom or robot will be ineffective. But we will see that in addition, the flow of the pump counts just as much.

The main points to check when choosing a pump for the swimming pool (of which it is the main equipment) are the following:

  • The volume of water in the basin,
  • The filtration capacity,
  • The distance that separates the technical room from the swimming pool, knowing that the smaller it is, the better the filtration device works,
  • The configuration of the piping, the elbows which can slow down the flow.

Thus, we choose this material by paying great attention to the following specificities.

Pump flow

This flow is expressed in m3/h (cubic meters per hour). It indicates the amount of water who can be filtered in a specified period. It is given taking into account the complete recycling of the volume of the basin in 4 hours: for example 100/4 for 100 m3 in 4 hours or 25 m3 per hour.

Small difficulty all the same: for a swimming pool installed in a green settingso in the immediate vicinity of trees and plants of all kinds, you should know that debris (leaves, stems, faded flowers, etc.) cause a increased water fouling and it should be taken into account when choosing your pump because this factor makes it necessary to higher filtration rate to the one suitable for the same pool installed in an area without plants.

It is therefore considered in this case that a clogging coefficient must be applied to find the most suitable model. It is generally of 1.20 and it must be integrated into the calculation making it possible to know the required pump flow rate. This is obtained by multiplying the flow rate per hour by the coefficient, ie in the example cited above: 25 x 1.20 = 30. The desired flow rate is therefore 30 m3/h.

It should be checked that the type of filter is compatible with this flow rate. Coal and sand do not impact this flow in the same way. This is the type of indication that must be given to the consumer.

The power of the pump

The rotation being initiated by the motor, it must be powerful enough otherwise the water will not be able to circulate in the filtration system. This power is expressed in CV and its consumption Watts (W), knowing that 1 CV corresponds to 0.735 kW (1 kW = 1000 W).

The power of the pump is related to the flow. The life of a powerful pump with a low flow rate used in a large swimming pool is considerably reduced. The choice must therefore take into consideration all these crucial data.

You can keep in mind the indicative data which can be found in the following small correspondence table, where the volume of the swimming pool takes into account a pressure drop of 20% compared to the theoretical volume.

Pool volume (recommended)


Minimum recommended flow

25 m3

0.37 kW – 0.5 CV

Between 7 and 8 m3

37 m3

0.55 kW – 0.75 CV

Between 11 and 12 m3

50 m3

0.75 kW – 1 CV

15 m3

75 m3

1.10 kW – 1.5 CV

22 m3

85 m3

1,50 kW – 2 CV

Between 25 and 26 m3

95 m3

2.20 kW – 3 CV

30 m3

You can opt for a slightly higher flow rate than expected if the piping has many bends, as this can affect the operation of the pump.

It makes sense to choose a quiet pump so that it does not harm the comfort of pool users and also respects the tranquility of the neighborhood. This data is expressed in dB (decibels).

Finally, it should be noted that pumps are completely incompatible with certain types of basin. It is of course possible to seek advice from a swimming pool specialist before buying a pump because this professional knows perfectly the necessary equipment depending on the model and size of the swimming pool, the type of filtration, the configuration of the pipes, etc. especially if he built the pool. To avoid choosing your pump despite common sense, you can follow his recommendations with his eyes closed.

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