How Often Should You Backwash a Sand Filter

Backwashing your sand filter is an important process in maintaining the performance and operation of your filtering system Being familiar with the sights and sounds of your filter pump and equipment can give your pool water the most efficient water treatment while saving electrical energy. How often should you backwash a sand filter?

As a general rule of thumb, you should backwash and rinse your filter about once a week or after you vacuum high usage,  or according to the filter’s system pressure gauge if it rises above 8-10 psi above baseline or normal operating pressure.

A sand pool filter uses sand as a filter media to trap particles in the pool water as it flows through the sand. The sand in a pool filter is usually #20-grade sand, which is specially sized and shaped to capture particles in the 20-100 micron range. As the sand collects more particles it becomes less efficient, collecting more and more dirt in the sand until its backwashed.


How Often Should You Backwash a Sand Filter


Typically, you will backwash your pool once per week during the summer season as a general rule of thumb maintenance procedure or when the pressure gauge on your filter is at 8-10 PSI  above the normal operating pressure level.

Sponsored Ad - UHARBOUR Water Pressure Gauge, Glycerin Filled Pool Filter Pressure Gauge 0-50 PSI/350KPA,2" Dial and 1/4"N...The answer is always different for every pool owner regarding how often should you backwash your pool, and check your PSI on the filter vessel because every pool and filtering system is different.

If the filter runs well at 1o-12 PSI and then goes up to around  18-20 PSI, your pool sand filter needs a backwash. After a while, you’ll know the typical operating pressure for the system and monitor it daily as part of your maintenance check.

PSI (pounds per square inch) measures your filter’s operating pressure. Pool filters have a pressure gauge that indicates your PSI, which varies depending on your pool and other variables.  Find out your filter’s baseline pressure and keep an eye on it every time you check your chemistry levels or perform maintenance.

Variables can be:

  • Pool Usage
  • Rain & Storms
  • Temperature

The frequency of backwashing depends on how much use your swimming pool gets and the type of filtration system as well as its position.  The warmer it gets the more usage the pool gets and the more chemicals are used up, the more you’ll need to backwash.

As a general rule of thumb, you should backwash and rinse your filter about once a week. The optimal time is right after you vacuum the pool. However, if your pool has had a lot more use than normal, it may be necessary to backwash it once a week. You can also tell when it is time for a backwash by checking the sand filter system’s pressure gauge.

If your pool is surrounded by gardens, shrubs, or trees, it’s likely to need more regular backwashing than a pool that isn’t subjected to leaf pollen, dust, and organic debris blown off by trees and shrubs located around the swimming pool.


How Long do you Backwash a Sand Filter

You should backwash a sand filter for approximately 2-3 minutes or until the sight glass located on the top of the pool filter underneath the pressure gauge turns clear after which turn the system and set the multi-port position to rinse for around 30 seconds-1 minute.…………………………………….read more



How to Backwash a Sand Filter?

  • Turn the filter system’s power off
  • Attach backwash hose
  • Set to Backwash position on the multiport valve
  • Turn the filter on & backwash for 2-3 min or until the sight glass clears.
  • Turn the filter off again
  • Set it to the Rinse.…………………………………….read more


The age of the sand media can determine how often you backwash because the newer the sand is the more efficient and the more it catches debris and oils building pressure faster. After changing sand in the filter you will notice that the pressure comes up quickly but will level out after running for a few days.

If you notice your pool water is a little cloudy or see debris floating around in the pool, it most likely implies that your filter isn’t working as well as it should and should be backwashed. You may also notice high total dissolved solids (TDS) levels that will visually be cloudy water when you test pool water samples and chemistry levels.

Another indication that you need to backwash your filter is if there’s a drop in its regular flow rate or GPM (gallons per minute). Every filter and pump has its standard GPM, usually determined in your manufacturer’s guide and manual. You can also find it by searching for your particular model # on the internet.

Backwashing the water in your pool on a regular basis or when needed can help make your sand filter run more efficiently and keep your pump operating at cooler temperatures pulling fewer kilowatts for savings that are accumulated over the summer season. 


How do you clean pool filter sand

  • Set filter to Backwash
  • Switch Pump off
  • Open pump lid & pour sand filter cleaner into strainer basket.
  • Turn the Pump on for 15 Secs moving sand cleaner from the pump to the filter tank.
  • Turn Off
  • Leave off for 8 hours & let cleaner work in tank.……………………………….read more


JimGalloway Author/Editor



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