How to Clean a Pool Filter
Your filtration system plays an important role in your pool maintenance. The filter system not only gets rid of dirt and debris in the swimming pool, but also helps fight algae. Keeping your filter clean makes sure your pool always looks good. In this how-to, we go over the step-by-step DIY of cleaning pool filters

There are 3 different types of pool filters. Diatomaceous Earth (D.E. for short), Cartridge and Sand Filters. Each has its own unique method of cleaning.

Example of a Sand Pool Filter Setup

Example of a Cartridge Pool Filter partially broken down

Example of a D.E. Pool Filter Setup

Two Methods of Cleaning Pool Filters

There’s two methods to cleaning filters: backwashing and breakdown cleanings.

Backwash Filter Cleanings (Sand and D.E. Pool Filters)

Sand and D.E. Filters can be “backwashed”. Backwashing is reversing the flow of the filter.

When you reverse the flow, the debris that is trapped in the filter medium gets pushed out. When you perform a backwash, the debris will get dumped to waste – preventing it from returning to the pool (which would defeat the purpose).

D.E. and Sand Filters should be backwashed at least once a month. Also, if filter pressure rises by 10 psi over the initial reading then it’s time to backwash too.  

Before backwashing, you should raise your water level.  This is because during the backwash you’ll be pumping to waste and losing some water.

Break Down Cleanings (Cartridge and D.E. Pool Filters)

Cartridge and D.E. Filters require periodic breakdown cleanings of the filter (For D.E. filters, this at minimum every 6 months). This means you’ll need to take apart (“break down”) the filter unit. 

Sand usually doesn’t require break down for cleanings – only backwashing. However, you may need to break down your sand filter to replace the sand (at least every 5 years if not sooner) or diagnose a problem (such as sand entering the pool from the returns).

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Sand in filters wears out

Sand wears over time. Just like water polishing a rock in a river, sand becomes polished in a filter. The smoothness of the grains allows debris to pass more easily through it making it filter less. 

This is why you need to change sand every few years. If you have a tough time keeping the water clear despite having everything balanced, it might be time to change your sand.

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Always check the filter manual

While filters are mostly the same, there might be something unique to your pool filter. It’s always recommended that you check out your filter manual for specific manufacturer’s instructions.

How to Backwash Sand and D.E. Filters.

steps

minutes

Step 1: Turn of system

Turn off the pool pump and prevent it from turning on automatically.

Step 2: Turn valves to backwash

If you have a push/pull valve, pull the handle to the up position.  If you have a multiport valve, move the handle to the backwash position.

Step 3: Start Pump

Turn the power to the pump back on and run the pump for 45 seconds to 1 minute.

Step 4: Turn off pump

Turn off the pump again.

Step 5: Turn valves to rinse or filter

If you have a push/pull valve return it to the down position.  If you have a multiport valve, move the handle to the rinse (if available) or filter position.

Step 6: Start Pump

Turn the power to the pump back on and run the pump for 45 seconds to 1 minute.

Step 7: Repeat 3 times

Repeat steps 2-6 for 3 cycles. If you have a D.E. filter you will need to add D.E. once backwashing is complete.

Backwashing Do's

  • Backwash when filter pressure raises 10psi or more
  • Turn off the pump when moving valves. 
  • Review the filter manufacturer’s manual

Backwashing Don'ts

  • Don’t turn valves with the pump on.

 

How to Break Down and Clean a D.E. or Cartridge Filter

steps

minutes

Step 1: Turn of system

Turn off the pool pump and prevent it from turning on automatically.

Step 2: Bleed Air from the system

Release the air out of the filter by opening the air relief valve at the top of the filter.

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WARNING

Failure to release trapped air can cause the lid to blow off causing damage and severe injury – even death.

Step 3: Remove Band Clamp

The filter will have a band clamp that connects the top and bottom of the filter, using a tool appropriate for the size of the nut on the band, loosen and remove the band clamp.

Step 4: Remove Grids/Cartridges

Once the top has been removed, it is time to remove the filter grids or cartridges. Remove any clamps securing the grids/cartridges in place and carefully remove them from the filter housing.

Step 5: Clean Grids/Cartridges

Using a hose spray the DE off the grids or spray between the pleats of the cartridges.  If oils or stains are present, use a filter cleaning agent to spray down the grids or pleats and allow the solution to sit for the recommended time. Repeat as necessary.

TIP: Use gentle pressure

Avoid using high pressure to wash the filter grids/cartridges. Too high a pressure can tear the filter medium and require replacing the grid/cartridge.

Step 6: Check for Damage

After the grids or cartridges have been cleaned, inspect each for any damage. This includes broken grids, holes in the material over the grid or torn pleats. If you find damage you’ll have to replace the filter grid or cartridge. In addition, check the manifold – (where the D.E. and cartridge grids fit into) for cracks and ensure the o-rings are pliable and not stretched.

Step 7: Put grids/cartridges back in place

It’s time to put the grids/cartridges back in the filter.  D.E. grids and cartridges will sit on a manifold at the bottom of the filter housing unit. For D.E. grids follow the diagram in the filter manual or on the housing, making sure the small grid is in the proper place.  Cartridges have one hole for each cartridge unit.

Step 8: Reassemble Filter Housing

Place the top half of the filter back on, making sure that the o-ring is in place and lubricated.

Step 9: Tighten Clamp

Place the band clamp back in place and tighten.  Leave the air relief valve open.

Step 10: Run the pump bleeding air

Once everything is in place, turn the pump back on and when water begins coming out of the air relief valve, close the valve.

TIP: Check for leaks

With the pump running, check the filter to ensure that there are no leaks around the band clamp.

Break Down Cleaning Do's

  • Bleed any air from the filter using the air relief valve.
  • Use light pressure to clean grid/cartridges
  • Check grids/cartridges and filter manifold for damage.
  • Check o-rings and replace as necessary.

Break Down Cleaning Don'ts

  • Don’t attempt to disassemble filter housing with air in system. This can cause the filter lid to blow off and result in severe injury and damage.
  • Don’t use high pressure to clean cartridge/grids. This may cause damage.
  • Don’t put damaged cartridges back into filter.  

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How to Clean a Pool Filter

Your filtration system plays an important role in your pool maintenance. The filter system not only gets rid of dirt and debris in the swimming pool, but also helps fight algae. Keeping your filter clean makes sure your pool always looks good. In this how-to, we go over the step-by-step DIY of cleaning pool filters

8 Comments

  1. Mike Flowers

    What kind of filter cleaning agent do you recommend for cartridge (pleated) filters?

    What kind of lubricant do you recommend for the O rings?

    • Scott Hamilton

      Hi Mike!

      Excellent questions!

      I don’t have a specific recommendation for filter cleaners. Most of the time, simply hosing off the debris should work. I know there are filter cleaners on the market, I just don’t have enough first hand experience with any particular product to make a valid recommendation.

      For lubricant on the O-ring you can just use petroleum jelly.

      Thanks!

    • Bill Burns

      For 25 years I owned a pool cleaning and repair business. The Pool Doctor, Inc.. to thoroughly clean pleated filter cartridges, it’s a 2 part process. 1st step is to degrease with dawn dish detergent and rinse well. The second step is to descale by rinsing with muriatic acid. I

      • Scott Hamilton

        That’s great advice Bill! Thanks for sharing!

  2. Steven A. Smith

    After many enjoyable years of enjoying my Doughboy Pool, I have upgraded to an inground pool. I am looking forward to seeing updates on pool maintenance, and troubleshooting.

    • Scott Hamilton

      Hi Steven!

      Congratulations! Inground pools can sometimes present different challenges than vinyl above ground pools, but for the most part maintaining them both is relatively the same.

      Make sure to subscribe and we’ll keep you updated on new articles we post.

      Thanks again and enjoy your new pool!

  3. Duane Rutherford

    I have a 15,000 gallon in ground pool that uses a 175 sq/ft cartridge pleated filter is this adequate

    • Scott Hamilton

      Hi Duane,

      The suggested minimum for 15,000 gallons would be 150 sq/ft, so with 175 sq/ft you’re good to go!