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Most pools either have a D.E., cartridge, or sand filter. Each of these filtration systems needs to be cleaned and maintained so they can keep your water clear and sanitary!

But each type differs from the other. Backwashing sand filters is the easiest, but diatomaceous earth or D.E. filters are similar. Cartridge filters are the only type that you can’t backwash, but you still need to clean them!

We’ll help you find out how to backwash a pool filter and keep your pump working smoothly!

What Does it Mean to Backwash a Pool Filter? 

The backwashing process is a term that loosely means cleaning your filter system. As your pool filters out debris from your pool water, it snags certain particles, oil, and bacteria.

The filter’s media gets contaminants stuck inside it during this process. This makes your pool water clean and sanitized, but it makes the filter medium dirty. When these particles build up over time, they can impede your pool filter’s ability to clean your swimming pool.

Backwashing your pool filter system rinses these particles and debris from the filter medium. The dirty water and particles are flushed from your pool’s pump onto your lawn or another depository.

To properly backwash your pool filter, you need to know what kind of filter system you own. Most pools have sand filters, D.E. filters, or cartridge filters. How you clean these systems depends on the filter media your filter system has and the type of valve handle on top of the pump.

How Do You Backwash a Pool Filter? 

Sand filters are the most common type of pool filter system. They utilize pool sand in the filter container, where the pool skimmer pulls water and pushes it through the sand medium.

To backwash a sand filter, follow these steps:

  1. Attach your pool backwash hose to the dispenser of the backwash port
  2. Switch your pool filter from filtration to backwash
  3. Turn your pool filter back on
  4. Let the water flow out through the backwash port
  5. The water should flow until it comes out clear
  6. Switch your multiport valve to rinse
  7. Rinse for about 30 seconds to a minute
  8. Turn your multiport valve handle back to “filter.”

Backwashing a D.E. filter is very similar, with some minor adjustments. D.E. filter sand is much more effective at collecting debris and particles in the water. You might need to rinse your D.E. filter sand 4-6 times before it’s cleaned. But the process is essentially the same.

Cleaning cartridge filters is very different. A cartridge filter system doesn’t use sand or D.E. sand to filter debris. Rather it uses filter grids to catch particles as they move through the system.

You need to remove cartridge filters and clean them individually with the hose and filter cleaner. Once they’re cleaned, return them to the pool pump and return your filter handles to the filter setting.

How Do You Know It’s Time to Backwash a Pool Filter? 

The best way to decide if it’s time to clean your pool filter is if the pool looks dirty. Ideally, you’ll catch the signs before the water gets dirty, but dirty pool water means it’s time to backwash your pool filter.

When the pool sand or filter medium gets too dirty, it can no longer pull contaminants from the water. Thus, your pump will just be pumping dirty water back into your swimming pool.

The pump’s speed on the meter might be low, too, since the machine will be working harder to filter water. If your pool filter is working properly, the meter should show it’s filtering at a high turnover rate.

If the pool’s struggling to filter all the water within a day, it’s time to backwash your pool filters. If you want to learn more about pool filters and turnover rates, you should check out our article on how long to run your pool pump!

How Do You Know When Your Done Backwashing a Pool? 

The best way to know you’re finished backwashing your pool is to see clear water flow from the pump. Let the pool water backwash until it comes out clean or until the water in the sight glass looks clear.

It usually only takes approximately 30 seconds to 2 minutes to thoroughly backwash a pool. But, let the water flow until you see clear water flow.

How To Replace Filter Media in Your Filter System? 

To replace sand filters, buy silicon or glass pool filter sand. Once you have the right medium, follow these steps to replace your filter medium:

  1. Turn your pump off and let your filter media dry out overnight through the drain port
  2. Vacuum the sand from the filter
  3. Be cautious when vacuuming near the base of the container so you don’t damage anything
  4. Add the new sand
  5. Return the cover to the container
  6. Rinse or backwash your new media to remove any excess dust

Filter cartridges are pretty easy to replace. You’ll need to buy new cartridges, remove the old ones, and replace them with new ones. The most important thing is finding the right size cartridge to replace your old ones.

Replacing DE filter sand is similar to replacing regular filter sand. Except, DE filters usually have a slightly different setup. You’ll have to remove the cartridge holding the D.E. sand filter and remove the old filter grids.

Remove the old D.E. sand filter and replace it with new diatomaceous earth. Reassemble your cartridges and rinse or backwash the new earth before starting your filter.


Always check that your pool pump is working under normal operating filter pressure. Monitor the gauge to ensure you know the average pressure versus what is slower or lower than average.

If you have trouble keeping track, use a planner or the calendar on your phone to track when you least backwashed your pool. This is one of the best ways to stay on top and prevent your pool from becoming full of contaminants!

If you’d like to learn more about proper pool maintenance, check out our blog for more!


How Often Do You Need to Backwash a Pool Filter? 

You should try to backwash a pool at least once a week. This will ensure the water flows smoothly and your pool stays balanced. Your pool pump and filter prevent debris from polluting your water and upsetting the water chemistry.

Do You Need to Backwash a Cartridge Filter?

No, you don’t need to backwash a cartridge filter. You must remove them, spray them with filter cleaner, and rinse them with the hose.

Are Pool Filters Delicate?

While a pool filter isn’t delicate, you must be careful when cleaning your pump and filter. The parts can break or crack if you’re mishandling the system or gruffly handling anything.

Do You Need to Have a Backwash Hose?

No, you don’t need to use a backwash hose. But your backwash valve will probably leave a big mess on your lawn. The water will likely pool in one spot and mess up your grass or gardens.