#### Why is the flow rate of the swimming pool filtration pump important?

Determining how to choose the swimming pool filtration pump that best suits your pool requires that you look at several criteria. Power and flow rate are fundamental data to take into consideration before taking a closer look at the specificities of the machine, its quality, etc. Let's start first by defining the flow rate that the swimming pool filtration pump should have. What is the calculation and what are the factors that can reduce the flow?

#### What is flow?

The flow rate of the filtration pump is the volume of water that the machine must be able to filter in a given time. It is expressed in mᶾ/h and must be proportional to the volume of water in the pool.

##### How to calculate the flow rate of the swimming pool filtration pump?

First of all, you need to know the volume of your pool or calculate it. If it is rectangular with a flat bottom, the Volume = Length x width x water depth.

If the bottom is at several levels, it is possible to take the average depth.

If the pool is round with r = radius and h = water height, here is the formula V = (π x r)^{2} x h

It is common practice to say that all of the water in the swimming pool, to be perfectly cleaned and disinfected, must ideally be recycled within 4 hours.

The basic calculation is as follows: Flow = Volume of pool water / Number of hours defined for total recycling.

For example, for a 75 mᶾ pool, you need a filtration pump with a flow rate equal to 18.75 mᶾ/h, because in fact 75 mᶾ / 4 hours = 18.75 mᶾ/h.

##### What factors should be taken into account to define the flow rate of the swimming pool filtration pump?

The flow rate of the filtration pump must be compatible with that of the filter. The flow rate of the filter must be at least equal to that of the pump, ideally it is even a little higher. If the flow rate of the pump is greater than that of the filter, the water passes too quickly through the filter mass. As a result, it does not properly retain all impurities.

If the hydraulic robot is your pool cleaning tool, you must check its compatibility with the flow rate of the filtration pump.

##### When to increase the flow rate of the swimming pool filtration pump?

For a more reliable calculation of the flow, it is necessary to take into account the environment, the configuration of the pipes or the distance of the technical room from the pool.

If the pool is surrounded by vegetation, more leaves, flowers, twigs and insects will invade the pool. It is therefore necessary to increase the flow rate of the filtration pump. To do this, we apply a clogging coefficient. We multiply the initial flow by 1.20. In the previous example, the flow rate of the filtration pump is 18.75 mᶾ/H. The rectified flow rate will therefore be 22.50 mᶾ/h (18.75 mᶾ/h x 1.20 = 22.50 mᶾ/h).

The water flow rate at the outlet of the discharge nozzles is lower than that of the filtration pump. In fact, the more elbows and tees there are on the pipes, the more length of pipe there is, the more the water will be slowed down by these obstacles. It is important to take into consideration and slightly increase the pump flow rate.

The flow rate of the filtration pump is an essential concept to absolutely take into account. Carefully calculating and choosing the right flow rate for your swimming pool pump ensures crystal clear water and the perfect functioning of the entire filtration system.

To correctly choose the swimming pool filtration pump best suited to your installation, it is also important to know what power for the swimming pool filtration pump to take into account. Different types of swimming pool filtration pumps exist. To help you in your choice, let's compare the centrifugal versus self-priming filtration pump and analyze the differences between single speed filtration pump versus variable speed pump.