What pool filters need to be backwashed?

Author: Khalid Predovic  |  Last update: Sunday, May 10, 2026

Both sand and DE filters need to be backwashed every once in a while. Cartridge filters don't need backwashing. And let's be clear -- a pool filter is not the same thing as a salt water system, should you have one. Some pump and filter systems include built-in saltwater components.

Do all pool filters need to be backwashed?

Cartridge filters aren't designed to be backwashed, so don't even try! Unlike sand filters, there's no reverse water flow function (or backwash line), so you'll have to clean them manually.

How often should a pool pump be backwashed?

Backwashing should be a part of your weekly pool maintenance, and the best time to backwash is after vacuuming. You may need more frequent backwashing if your pool has collected a large amount of debris or other contaminants. Birds, trees, and heavy rains can make your pool prone to require more frequent backwashing.

What happens if you don't backwash the pool?

Don't Wait Too Long to Backwash:

On the flip side, not backwashing enough can also reduce flow and lead to cloudy water, as not enough water moves through the filter system.

How often should I backwash my water filter?

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.

How To BACKWASH A POOL FILTER (The Right Way)

How do you know when you need to backwash?

Another industry standard is to backwash when your filter's pressure gauge reads 8-10 PSI (pounds per square inch) over the starting level or “clean” pressure. For example, if your filter is running normally at 15 PSI but increases to 25 PST, you should perform a backwash.

What happens if you don't rinse after backwash?

Don't forget to rinse! Rinsing for 30 seconds after backwashing pushes the sand back in place clearing the filter of loose dirty water. If you don't rinse, you will have a puff of dirty water coming through the jet and back into your clean pool.

Do I backwash after shocking the pool?

If you're dealing with an algae infestation, brush the pool after shocking to remove lingering debris and run the filter. Rinse or backwash your filter to avoid recontamination. If you've still got traces of algae, shock your pool again.

Can you backwash a pool filter too much?

As eluded to above, if you backwash your pool pump for too long, it runs the risk of introducing air into the system. Air pockets can cause pumps to lose the constant flow of water that they need to keep working. If this happens to your system after a backwash, you may need to prime your swimming pool pump.

Should I run my pool pump on filter or recirculate when adding chemicals?

If you want to distribute chemicals throughout the pool, without risk of clogging the filter, running your pump on recirculate for 2 hours should be sufficient. Of course, if your filter is faulty you should aim to replace it as quickly as possible, so as to avoid excessive build up of solid particles and debris.

Do I need to add de after every backwash?

You MUST add new D.E. every time you backwash a D.E. filter or it will lose its effectiveness to clean the water. It is suggested that you backwash your multiport D.E. filter after you vacuum. If necessary, do so before and during vacuuming but remember, add D.E. to skimmer EVERY TIME YOU BACKWASH!

How often should I shock my pool?

Shocking your pool regularly will help to keep the water clean and free of contaminants. You should aim to shock your pool about once a week, with the additional shock after heavy use. Some tell-tale signs that your pool needs to be shocked are cloudy, foamy, green, or odourous water.

How do I know if my pool pump is dying?

Noise - Any noises that are out of character are an early warning sign that you might need a swimming pool pump replacement. Clogged pool filter pumps will be unable to draw in enough water, something that can cause them to vibrate excessively, producing a rumbling sound.

What is the filter backwash rule?

What is the Filter Backwash Recycling Rule? The FBRR requires filtered surface water suppliers using conventional or direct filtration to, where needed, change the return of recycle flows in their plant's treatment process.

What is the ideal level of chlorine in a swimming pool?

Regardless of how frequently or what system you use to add chlorine to the water, the chlorine level should stay between 1.0 and 3.0 parts per million (ppm) to maintain a healthy pool. Anything higher will make you run the risk of red eyes and swimmers itch.

Should you vacuum pool on backwash?

While it's not strictly necessary to backwash before vacuuming, doing so can significantly enhance the efficiency of your vacuuming efforts.

Does backwashing remove algae?

Use a vacuum or backwash the pool to remove the dead algae. Apply a mustard algaecide following the label directions. Allow the water to circulate for 24 hours. Use a pool vacuum or backwash the pool again to remove the remaining dead algae.

What psi should I backwash my pool?

Updated for 2018. For decades, pool professionals have learned to backwash or clean the filter when the pressure reading increases 10 psi above starting or clean pressure. The growing use of variable-speed pump technology requires a change in this long-understood “rule.”

Can shock clog pool filter?

While some mistakes are small and recoverable, adding pool shock through your skimmer will literally blow up your pool's filter system! The gasses created from the mixture of dichlor and chlorine chemicals in such a small chamber create a deadly explosion.

Do I vacuum the pool after shocking?

Vacuuming After Shocking

Running the water pump during this period will allow the shock to do its job. After 24 hours, debris that was disturbed during your previous vacuuming may have settled back to the pool floor, so giving it another vacuuming will get rid of most of the dirt.

Is shock the same as chlorine?

1) What is the difference between chlorine and shock? Do I need to use both? Chlorine is a sanitizer, and (unless you use Baquacil products) is necessary for maintaining a clear and healthy pool. Shock is chlorine, in a high dose, meant to shock your pool and raise the chlorine level quickly.

Do you add algaecide or shock first?

Let the shock try to fight the algae first. Add algaecide about 24 hours after shock to finish the job and prevent future algae blooms.

Why does my pool get cloudy after I backwash it?

You should backwash most sand filters every 2 weeks during winter and every week during summer. This also applies to cartridge filters as well. However, backwashing more frequently than this can lead to excessive sand loss, cloudy water, and poor filtration.

Why is my pool filter blowing out sand?

The reason why you're finding sand in your pool is that the sand filter media of your pool filter is somehow coming back through your pool's return lines. And that's a problem. It means that some section of your pool filter is broken and leaking sand out.

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