How to Clean a Pool Filter

Circulation is very important in swimming pool maintenance.  This includes adequate pool pump run time and a clean swimming pool filter.  A good rule of thumb is to clean your entire filter every 6 months.  More precisely, is when your clean starting pressure gets to be 8-10 pounds per square inch (PSI) above.

Pro Tip:  No two pools will have the exact clean starting pressure.  Clean starting pressure is where your PSI is when the filter has just been cleaned.  Most filter gauges have a dial you can turn.  If not, you can mark it with tape or another method.

All swimming pools have a main circulation pump and a pool filter.  As the water gets drawn from the skimmer and/or main drain, it is then pushed through your various pieces of equipment, including the pool filter where dirt and debris get captured.  Letting your PSI get too high can lead to algae or actual damage of the filter elements.  There are 3 types of filters.  Here is how they each need to be cleaned.

Sand Filters

Sand filters need to be cleaned the least often.  They are backwashed for years before a complete filter clean is needed.  Typically, your sand filter will have a valve with several (up to 6) different outlets.  These are known as a multiport valve.  You would utilize this to bypass the filter and to backwash.  If it has been 2-3 years, you probably want to do a sand change.  Otherwise you risk breaking the laterals at the bottom of your filter that old up the sand, which does the filtering.

We start with the valve.  Hopefully it was installed with unions because it needs to be removed.  Otherwise it will need to be cut out and re-plumbed.  You’ll want to make sure you have all of the needed supplies including #20 silica sand, the tank o-ring, teflon tape and pool lubricant.  If you were forced to cut out your valve you will also need unions so you don’t have to go through that again.  Check your instruction manual to verify how much sand you will need.  Silica sand usually comes in 50 pound bags.

Make sure the pump is off!  The filter tank’s pressure needs to be released by turning the drain cap at the bottom of the filter.  Remove this completely.  Unscrew the bolts to remove the tank clamp.  Gently lift off. Next is the not-so-fun part of scooping out the sand.  Check your laterals to make sure none are broken.  Sometimes laterals get clogged so soaking them in a bucket of water is not a bad idea.  

Use your garden hose to rinse out the tank.  Replace the drain cap.  Fill the tank with water to form a cushion for the laterals as you add the new sand back in.  About halfway is good.  Next, do everything in reverse  For a more detailed description, check out our blog 

Check read this article to learn how to fix your sand pool filter.

Cartridge Filters

While the worst at filtration, cartridge filters are by far the easiest to clean.  Turn off the equipment!  Remove the tank clamp.  Gently lift off of the lid and put it aside.  Completely remove all of the cartridges.  There are two different ways to clean your cartridges.  One type of filter cleaner is a spray and rinse.  For extra dirty cartridges, you may want to buy the kind of cleaner you add to a bucket of water and soak your cartridges.

Rinse off the cartridges with your garden hose.  They sell special nozzle attachments designed to get in between the pleats.  Inspect your cartridges for broken bands and other damage.  If the pleats are not evenly spaced or more than one band is broken, you will need to replace your cartridge(s).  If they still look oily or greasy after cleaning would be another reason to replace.  You can put the cartridges back in wet because they're going to get wet anyway.  Replace the cartridges.  Lubricate the tank o-ring.  Replace the lid and the clamp.  Turn system back on and check for leaks.

Pro tip:  It is a good rule of thumb to replace your filter tank o-ring every other filter clean.

Diatomaceous Earth (DE) Filters

These filters offer the best filtration, but can be a pain in the butt to clean.  DE filters come with a top mount manifold or a bottom mount manifold.  A manifold is what holds the grids into place.  Bottom mount DE filters have 8 of the same size grids.  Top mount filters have 7 full size grids and one partial.  A very detailed blog is available on our site, so here we will just do a quick rundown.  The blog on cleaning a DE filter-the right way can be found here 

Turn off the equipment!  Remove the clamp assembly and set the band clamp aside.  Remove the lid of your filter.  Remove the manifold.  Remove all the grids separately.  You may be tempted to lift out the assembly and leave the grids attached.  Don’t.  A full filter clean requires we hose off BOTH sides of the grids and check for damage.

Rinse the old DE off in a safe place.  Since DE is natural, many people will use their lawn.  Be sure to follow your city’s guidelines.  Inspect the tank o-ring for swelling or flattening.  Replace as needed.  Inspect all 8 grids for even the smallest of rips or tears.  See if any of the “ribs” are broken.  What we don’t want is to go through all of this work and have DE returning to the pool because we didn’t replace a grid we should have.  Replace any needed grids.  Don’t forget to check the manifold for cracks.  You should also replace your stand pipe o-ring regularly.  Re-install the grids and the manifold.  This can be tricky to line up.  Once the grids are seated properly, replace the lid and band clamp.

Add the appropriate amount of DE back through the skimmer with the system running.  If you have a 60 sq foot filter, you would need 6 pounds.  Have a 48 sq ft?  You would need 4.8 lbs.  Consult your owner’s manual for the proper amount for your filter.

Hire Someone

If you have never cleaned your pool filter before or just don’t feel like doing it, I suggest hiring a pro and watching how they do it.  It may give you the confidence you need to tackle it yourself next time.  See you poolside!

This article describes how to effectively backwash your pool filter. Want to know how to clean the bottom of your pool? Click here to read more.