Your Filter and how to Backwash

Your Filter and how to Backwash

There are two parts to a pool filter, the tank and the control handle which is called the Multi-Port Valve (MPV) the tank holds the media commonly sand or glass which filters the pool water.

During filtration, the pool water is circulated from the pool and through the filter, gravity pulls the water down through the media in the filter, the media catches and stops dirt & debris from being returned to the pool.

Over time the dirt & debris builds up which slows down the water flow and builds up pressure within the tank, the pressure gauge on the MPV will indicate when the filter needs a backwash to reduce the build-up of pressure and remove the dirt & debris that has built up.

Filter Settings

You will generally find these six settings in a pool filter.

  • Filter: This is the basic filter setting of the system and is used to vacuum the pool.
  • Rinse: This cleans the water filled inside the filter tank.
  • Circulate/Bypass/Recirculate: Used when you need to return the water back into the pool without making it go through the filter.
  • Drain/Waste: Opting the drain or waste setting will remove pool water without forcing it through the filter.
  • Backwash: This clears out debris, dirt and other contaminants that have accumulated in the filter, releases the pressure and sends water to waste.
  • Closed: If you choose this setting, then the flow of water to the pool and filter will be stopped. Make sure that you have turned off the pump before you set this option.


How to Backwash a Pool Filter

To perform backwashing on your filter, follow the steps below.

  • First, ensure that the pump is turned off.
  • Now, move the Multi-Port Valve Handle in a way that it sits on the ‘Backwash’ option.
  • Once done, switch on the pump.
  • You will now hear the water in the filter churning over, which will eventually run down the waste pipe. After about 2 minutes, you will see the colour of the water draining out has changed from murky to clear. And when that happens, switch off the pump.
  • Next, change the position of the Multi-Port Valve Handle to the ‘Rinse’ position.
  • Turn the pump back on and run on this setting for about a minute. The filter will now be filled with clean water.
  • Now, switch off the pump and move the Multi-Port Valve Handle to the ‘filter’ position.
  • Finally, turn pump back on to finish the backwashing procedure.

You need to ensure that the filter media is changed at the right times as per specifications, which is usually once every 4-5 years for the sand media and 8-10 years for glass. However, you may have to replace the filter sooner depending on the filtration process. Cartridge filters should have the filter element replaced around every 18 months.

Follow the steps above and your pool filter will remain clean and without any issues. If you face problems while trying to backwash, don’t hesitate to call for help. Check out this video from BioGuard as well for instructions on how to backwash your filter.


We at Poolcare help people fix their pool problems every day, give us a call 07 575 8471 and we will be happy to answer any of your questions