DE Filters: Backwashing the Filter  

by Pool Builders on 04-09-2011 in Articles

Backwashing your pool filter should be a normal part of your maintenance routine that will keep your pool water clean and safe for swimming. The frequency will vary according to the type and size of filter, the flow rate of the plumbing and the bather load of your pool. You will know that it is time to backwash the filter when the pressure reading reaches the level specified by the filter's manual.

Of the three types, Diatomaceous Earth (DE), sand, or cartridge filters, DE filters are generally the most effective in maintaining the cleanest possible pool, filtering down to about 3-7 microns. Keeping in mind that a micron smaller than 30 cannot be seen by the human eye, if you are using a DE filter to clean a cloudy pool, you may have to change your DE several times a day until the pool is clean enough to return to a normal maintenance routine. Nonetheless, between the three types of filters, DE does require the most maintenance.

If you are going to use this type of pool filter, it is imperative that you maintain a regular cleaning routine, backwashing whenever the pressure rises to eight to ten pounds above the normal operating pressure. Depending on the bather load, the elements around the pool that are naturally going to increase the amount of debris, and basic maintenance, it may be necessary to backwash as frequently as once a month, although backwashing is not generally needed that frequently.

Reading the manual for your filter will provide the most specific instructions for backwashing your DE filter, however, these instructions should provide you with a general idea of the process.


  • Clean the skimmer baskets
  • Turn off the pump and clean the pump basket. When you are finished, replace the pump basket and replace the lid.
  • With the pump turned off, put the backwash valve into the backwash position. If you are uncertain which the position this is, refer to your manual.
  • Turn the pump on again and run it until the water in the site glass runs clear. If there is no site glass, check to see that the water at the end of the backwash hose is clear.
  • Turn the pump off again and return the valve to the original, filter position.
  • Turn the pump back on and allow it to run for ten to 15 seconds. If there is a multi port valve, use the rinse setting.
  • Repeat the backwashing process two or three times in order to stir up any loose dirt that was not flushed with the first backwash.

When you have finished the backwashing process, and with the pump running, add about one pound of DE for every 12 square feet of filter space. If you are using a DE scoop, one scoop equates to one half pound of DE. Be sure to replace enough of the DE to avoid damaging the grids and receiving poor filtration for your pool.

For more information on pool filters, go to Pool Cartridge Deals.

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