how to clean pool filter

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How to Clean Every Type of Pool Filter

By Matt Giovanisci | Updated: June 22, 2021

It's only logical. Your filter is one of the main components in keeping your pool clean, so it also needs to be kept clean. But maybe you're new to pool maintenance. Or maybe you just got a new type of filter. Whatever the case, knowing how to clean a pool filter is an essential part of owning a pool.

But as long as you have the right equipment, enough time, and the desire to swim in a clean, clear pool (and who doesn't want that?!), cleaning your pool filter will be a snap.

How to Clean a Pool Filter Depends on the Filter

Depending on the type of pool filter you have—cartridge, sand, or diatomaceous earth (D.E.)—the proper cleaning method will vary.

Just make sure you have the proper equipment on hand for your type of filter, and then set aside some time to make sure it's done properly. A dirty filter makes for a dirty pool.

How to Clean a Cartridge Pool Filter

This is an easy type of filter to clean. That's because with a cartridge filter, you can most often simply pull out the cartridge, clean it, and replace it.

Still, you'll need to follow a few (OK, maybe more than a few) steps to make sure it's done right. You'll also need some equipment.

What You Need

Garden hose
Spray nozzle
Filter cleaner
5-gallon bucket, if needed
O-ring Lubricant
Replacement O-Ring, if needed
Replacement filter cartridge, if needed
Owner's manual, just in case

Once you have all the supplies you'll need, set aside some time to clean the pool filter. The process may even extend overnight, depending on how dirty the cartridge is.

Turn off the pool pump and the filter system.
Remove air from the system. Turn the air relief valve (usually located on top of the filter) slowly to remove any excess air from the system.
Remove the clamps (or other latching mechanisms) holding the filter together. If you're unsure how to open it, check the owner's manual.
Remove the top of the filter.
Slowly and carefully remove the cartridge and set it aside. Inspect it for damage and wear. If you find any cracks or tears, or it's past the point where cleaning will be effective, it's time to replace the cartridge.
Clean the cartridge: Use a spray nozzle on your garden hose to spray down the cartridge, making sure to get between the pleats. If the cartridge is really dirty, use a filter cleaner. Follow the manufacturer's instructions. If the cartridge is really dirty, soak the cartridge in filter cleaner overnight. Use a 5-gallon bucket, and make sure the cartridge is completely covered with the water and cleaner mixture.
Check the O-ring on the filter tank. If it's in good shape, lightly apply some lubricant to keep it that way. If it's dry-rotted or appears worn out, replace it.
Rinse the cartridge thoroughly.
Return the cartridge to the filter, and secure it in place.
Replace the filter top and close the clamps.
Turn the system back on, and open the air relief valve to release any excess air in the system. Keep the valve open until a steady stream of water sprays from it.
Check the system pressure to be sure it's in normal range. If the pounds per square inch (PSI) is off, you may have put the filter back together incorrectly, or something else may be wrong with the system. Troubleshoot the pool filter to identify and correct the problem.

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The Pool Care Handbook

How to Clean a Sand Pool Filter

This is a little more involved, but don't let cleaning a sand filter intimidate you to the point where you don't do it as often as you should. It'll only make the task more difficult when you do get around to it.

You have two options here. You can backwash the sand filter, which you'll need to do whenever it reaches 10 psi over the normal operating level. It may also be time to clean the filter if you start to notice cloudy pool water.

But at least once a year, you need to chemically clean your sand filter. To do this, you'll need a couple of supplies.

What You Need

Backwash hose
Sand filter cleaner
Owner's manual, just in case

In The Swim Liquid Pool Sand Filter Cleaner - 1 qt.

If you thought cleaning a cartridge filter was easy, just wait until you clean a sand filter!

Backwash the filter for 3 to 5 minutes to remove debris.
Turn off the pump, and turn the valve to Filter.
Remove the pump's strainer lid.
Pour sand filter cleaner into the strainer basket, and replace the lid.
Turn the pump on for about 15 seconds, just long enough to transfer the cleaner from the pump to the filter.
Turn off the pump, and leave it off for at least 8 hours, or overnight.
Backwash the filter for 3 to 5 minutes again to remove dirt and debris dislodged by the filter cleaner.
Turn the filter system back on.

If you don't already have a sand filter, you may want to consider investing in one. The time you'll save in cleaning is time you can spend enjoying your pool.

How to Clean a D.E. Pool Filter

This combines the processes of cleaning a cartridge filter and a sand filter. You can chemically clean a D.E. filter, almost like you would a cartridge.

Or you can backwash a D.E. filter, and just like the sand filter, it's time to do that when the filter's gauge reads 10 psi above the normal operating level. Cloudy water can also be an indicator that the filter needs a good cleaning. Aside from those indicators, it's a good idea to clean your D.E. filter at least once a month.

What You Need

Backwash hose
Garden hose
D.E. filter cleaner
O-ring Lubricant
5-gallon bucket
Diatomaceous earth powder
Muriatic acid (optional)
Safety goggles (if using muriatic acid)
Acid-resistant gloves (if using muriatic acid)
Owner's manual, just in case

Cleaning with D.E. Filter Cleaner

This is the quicker, easier, and less dangerous cleaning method.

Backwash the filter for 3 to 5 minutes to remove debris.
Turn the pump off.
Open the air relief valve.
Remove the drain plug, and let the water drain out of the filter tank.
Remove the clamps (or other latching mechanisms) holding the filter together. If you're unsure how to open it, check the owner's manual.
Open the filter tank.
Remove the filter manifold, and take out all the grids.
Rinse out the tank with the garden hose.
Clean the manifold: Use a spray nozzle on your garden hose to spray down the manifold, making sure to thoroughly flush the grids of all debris. If the manifold is really dirty, use a D.E. filter cleaner. Follow the manufacturer's instructions. If the manifold is really dirty, you may want to soak it overnight in a muriatic acid solution.
Use a garden hose to rinse the filter grids, flushing out all debris, including the D.E. powder.
Place the grids back into the filter tank.

Cleaning with Muriatic Acid

We recommend using this method if your filter is so filthy that regular filter cleaner isn't enough. And if you use this method, do so sparingly. Once a year is plenty.

Important: The acid in muriatic acid is exactly that. It's caustic, and can cause injury if you're not careful. Take all the precautions necessary to protect yourself, and anyone else who may be around while you're cleaning your filter.

Backwash the filter for 3 to 5 minutes to remove debris.
Turn the pump off.
Open the air relief valve.
Remove the drain plug, and let the water drain out of the filter tank.
Remove the clamps (or other latching mechanisms) holding the filter together. If you're unsure how to open it, check the owner's manual.
Open the filter tank.
Remove the filter manifold, and take out all the grids.
Rinse out the tank with the garden hose.
Clean the manifold: Use a spray nozzle on your garden hose to spray down the manifold, making sure to thoroughly flush the grids of all debris. Put on the safety goggles and acid-resistant gloves. We also recommend you wear long sleeves, pants, and closed shoes. Dilute the muriatic acid with water in a 5-gallon bucket. Follow the manufacturer's instructions for dilution. Place the manifold in the bucket, ensuring it's completely covered with the diluted solution. Allow it to soak overnight.
Use a garden hose to rinse the filter grids, flushing out all debris, including the D.E. powder.
Place the grids back into the filter tank.
Run the pool pump for at least 30 minutes to allow the D.E. to distribute evenly over the filter grids.

How to Add D.E. Powder to The Filter

Refer to your filter owner's manual to determine how much D.E. powder you'll need to add.
Prime the pool pump.
Remove the strainer basket lid.
Fill the basket with water, and allow some water to run through the incoming line.
Lubricate the O-ring inside the tank.
Replace the filter lid, and tighten the clamps or bolts to secure it.
Open the air relief valve to release excess air from the filter tank.
Turn on the pool pump.
Close the air relief valve when water starts coming out.
Mix the appropriate amount of D.E powder with enough water to make a slurry, which is a thin, creamy solution.
Make sure the pump is running.
Pour the slurry directly into the pool skimmer.
Run the pool pump for at least 30 minutes to allow the D.E. to distribute evenly over the filter grids.

If you've been wondering how to clean a pool filter, wonder no more! Keep the supplies on hand so you're always ready to clean the filter the minute you notice it's not working as well as it should.

And more than having clean pool water, keeping your filter clean will also help it run longer and more efficiently, saving you money, energy, and time. The longer you keep your filter in good working condition, the longer you can wait to replace it, and the more you can focus on enjoying your pool.

Happy Swimming!

Matt Giovanisci is the founder of Swim University® and has been in the pool and spa industry since 1995. Since then, his mission is to make pool and hot tub care easy for everyone. And each year, he continues to help more people with water chemistry, cleaning, and troubleshooting.

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