Backwashing a Pool DE Filter

Backwashing your D.E. filter can be a simple process by following a few quick and easy steps.  But before we go through the steps to backwashing it is important to answer a few questions:

"What is backwashing?" - Backwashing a D.E. filter is simply reversing the flow of water inside your filter tank.  When moving the backwash valve (explained in further detail below) the direction of the water in your tank is changed which allows for the dirt that has been collected to exit your tank.

"Why do we need to backwash?" - Similar to a vacuum cleaner, air conditioner filter, or your kid's bedrooms,  your pool filter collects dirt!  Whenever the filter fills up with the dirt/debris it reduces the flow of water to your pool.  Low flow = poor circulation which will lead to algae in the pool.  Bottom line, the filter must be backwashed on a regular basis to ensure that your pool water is clear.

"When do we need to backwash?" -  It is recommended to backwash your filter once every 4-6 weeks of regular use.  Additionally, there are several instances that would require backwashing in between the normal monthly backwashing.  1.) If your filter has been running for 48 hours straight without stopping then you will need to perform a backwash.  D.E. will "settle" onto your filter grids whenever it runs without stopping.  This can cause a buildup of pressure even if your filter grids are clean.  2.) If an abnormal amount of dirt, dust, or debris enters your pool water you will probably need to go ahead and backwash.  For example, a heavy rain washes sediment into the pool or a potted plant tips over into the pool.  3.) If the pool has had a heavy bather load for an extended period of time.  For example, 10+ ppl swimming every day for a week.  The amount of tanning oils, sweat, and hair products can clog up a DE filter.  

Other than these exceptions you can plan on backwashing monthly. Be sure to check your filter pressure before and after backwashing.  If your pressure remains higher than normal your filter may need to be disassembled and cleaned. Click here for more information on filter cleaning.

Now that you have some more information regarding backwashing let's get down to it.  Here are the steps to a standard backwash:

Step 1: Turn off pool equipment at the main power switch

Step 2: For slide valves - turn backwash handle and pull the valve piston straight up to the backwash position or for multiport valves – push handle down and rotate valve to the backwash position (see pictures A & B below)

Step 3: Turn equipment back ON

Step 4: Run equipment for approximately 60 seconds (the filter will be backwashing during this cycle).  If you have a sight glass (picture C) you will be able to see the dirty water flushing to your sewer. 

Step 5: Turn equipment OFF

Step 6: Return the valve to it’s original position NOTE: For slide valves be sure to lock it in the original position to ensure that it does not slide up during operation

Step 7: Turn equipment ON

Step 8: Repeat Steps 1-7 two more times, decreasing the amount of backwash time (60 seconds, 30 seconds, 15 seconds)

Step 9: Once you have completed the 3-cycle backwash you must add Diatomaceous Earth, also known as DE,  back into the filter.  This is accomplished by slowly pouring the appropriate amount into the skimmer while the equipment is running.  The DE will travel through the plumbing then into the filter.  The filter is now recharged with D.E. – replacing the amount that was backwashed out.

Step 10: Bleed any air out of the filter tank.  This is accomplished by opening the air bleed assembly on the top of your filter tank with the equipment running.  Typically, a filter gauge will be on top of the assembly and it may rotate with the assembly when opening.

These are the basic steps to filter backwashing.  It is possible that you could have a set-up different than what I have described here and, if so, please contact us.  We are happy to help in any way that we can.  

Thanks for reading and happy backwashing!