How to backwash your pool – a step-by-step guide

swimming pool filter
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Backwashing your swimming pool filter should be done as part of regular and ongoing pool maintenance. It can be undertaken by a professional. Or you can give it a go yourself if you following the steps in this post. 


What is backwashing a swimming pool filter?

swimming pool sand filter

Backwashing is the term given when the flow of swimming pool water is reversed. Instead of pumping through the filter,  into the swimming pool. The water is drawn from the pool through the filter to flush out debris and dirt that has accumulated.

Backwashing mainly relates to sand filters. However, recent years have sparked an increase in advanced filter media, such as OC-1 filter media and glass beads.


Why should I backwash my swimming pool filter?

Sand filters work by a process of ‘entrapment’. Dirt and debris from the pool are trapped in amongst the sand grains, becoming part of the filtering process. This increases filter efficiency to a point. However, over time, this causes a build up in pressure. And due to the consistency of sand can lead to ‘clogging’. Creating channels for water to pass through unfiltered. 

If this pressure build-up is not relieved the filter will become less effective. And collected dirt will end up back in the pool. Leading to unclean, unsafe and cloudy swimming water. 

Periodically backwashing dislodges these contaminants and disposes of them. This increases filtrationefficiency. And leads to a cleaner, safer swimming pool. 

How often should I backwash my swimming pool filter?

In normal circumstances, it is recommended that you backwash your swimming pool filter once weekly. Ideally, after the pool has been vacuumed and cleaned.

An indicator that your swimming pool filter may need backwashing is when the pressure rises approx. 8-10psi above normal operating pressure (you can determine base pressure after a backwash and work from this).

step-by-step guide to backwashing a swimming pool filter?

1: Firstly, turn the pump off. This makes the system safe to work on and avoids damage. Work should never be carried out with the pump on.

Your pool will likely have a multi-port with six different settings (filter, backwash, rinse, circulate, closed and waste).

Alternatively, it may have a ‘pull/push’ handle – in one position the water will flow normally through the filter. In the opposite, it will flow through the backwash hose.

2: Next, make sure all the valves in the backwash line are open

3: Then, turn the multi-port to ‘backwash’ – or turn the push/pull valve 180 degrees.

4: Turn on the pump.You will see water flow through the backwash hose.

Continue running this until the water visible in the side glass runs clear. Typically a couple of minutes.

5: Then, turn off the pump.

6:  Turn the multiport to ‘rinse’ (if you are using a multi-port – if not skip to step 9).

7: Next, turn on the pump and rinse (between 15-30 secs).

8: Turn the pump off.

9: Move all valves back to their original position. Move the multi-port back to ‘filter’ or turn the pull/push handle back around 180 degrees.

10: Finally, turn the pump back on and water should flow back towards the pool as normal.

In Summary

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Debbie Ekins
Debbie Ekins
Eagle Leisure - Sales & Marketing Manager Mission = to arm you with the knowledge you need to make the best buying decisions. Fuelled by coffee (and naps). Explorer of Scotland and the world.
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