How to Choose a Swimming Pool Pump in 5 Easy Steps

The swimming pool pump market can appear very complicated, so we have created 5 easy steps to help you choose the best pump.

Normally, you may consider replacing pumps like for like, however, if the pump has failed prematurely, it may have been the incorrect pump and we recommend following our 5 easy steps to choosing the correct swimming pool pump. There is a tendency for people to buy bigger pumps than necessary. This is not recommended as you will suffer higher running costs, and run the risk of overpowering the filter, straining the pump and causing early failure.

The importance is not necessarily the power of the pump (HP or kW) but the flow rate.

According to swimming pool experts, as a general rule, all the water should be filtered within an 8 hour period.

To choose your swimming pool pump you need to know how many litres of water are in the pool, and then match this with the flow rates of a pump.

The following steps are a simple guide on how to do this:

Step 1:

Calculate the volume of your pool.

Volume/m3 = Length/m x Width/m x Depth/m

If the pool is not all the same depth, you can use the average depth.

                                                               Same Depth:                                                                                             Different Depths:

Average Depth = (shallow depth +deep depth)/2

Please note these images are for a rectangular pool.

If your pool is circular, you can calculate the volume using the formula:

V=π r²h

Worked Example for Rectangular Pool (same depth):

If you had a 20m pool, which was 8m wide and 1m deep, the Volume would be:

V= 20m x 8m x 1m = 160m3

Step 2:

From step 1 you will be left with a value in metres cubed. This should be converted to litres.

1m3 = 1000 litres.

Therefore, multiply your volume by 1000 to give the figure in litres.

For the worked example, this would be:

160m3 x1000 = 160,000 litres

Step 3:

Calculate the required flow rate to circulate the pool in 8 hours.

As the water must all be circulated in 8 hours, you must divide the figure by 8 to give you the litres per hour figure.

For the worked example, this would be:

160,000L ÷ 8hours = 20000 L/h

Step 4:

Our pumps are rated in litres per minute, so the above figure must then be divided by 60 to give the litres per minute rate which can then be matched with one of our pumps, from either the SMP or SWIMM range.

For the worked example, this would be:

20000 L/h ÷ /60 mins = 333.3 L/m

 You now should have a figure which is the flow rate required in litres per minute. Our swimming pool pumps have this figure detailed.

Step 5:

Select a pool pump from our range of swimming pool pumps which matches your requirements. Ensure the pump has an adequate head for your system.

For the worked example, from the SWIMM range, the SWIMM 1000 would be suitable with a flow rate of 350 Ltr/min:

Please note:

The size of your pool filter is directly related to the size of your pump. If the filter is too small, this will put additional strain on the pump as it tries to force water through the filter and meets obstruction, causing friction. This may eventually cause the pump to burn out.

Most filters have a maximum flow rating. Ensure the pump does not exceed this. For example, if your pump output is 250 litres per minute, you should not pair this with a filter that has a maximum rating of 200 litres per minute.

Avoid downsizing the pipe for the pump as you run the risk of the pump running hot as it is starved of water.