How to Clean All Types of Pool Filters

how to clean a pool filter

One of your only jobs as a pool owner is to keep the water safe for swimming. 

This, of course, means doing everything you can to prevent accidents, but it also means keeping the water germ-free and healthy.

That can sometimes be an awfully big job if you’re doing it by yourself.

One of the things that makes it a little easier is a clean pool filter. If your pump system is working right, that filter will do a lot of the dirty work for you. 

Reasons To Clean A Pool Filter

Since the pool filter is responsible for keeping your water safe and germ-free, it’s extremely important that it’s always functioning at its best.

But aside from just filtering the junk out of your pool, keeping the filter clean is beneficial for a couple of other reasons.

For one thing, it can prolong the life of your filtration system. When the filter is clean, the pump won’t be overworked trying to do its job.

Secondly, it will help you save on pool chemicals. When the system is working well, you won’t have to keep adding chemicals to keep the water clean.

Types of Pool Filters 

There are three basic types of pool filters — sand, DE, and cartridge. They’re all pretty effective, but some pool wonders prefer one over the other for various reasons.

Sand Filters

Sand filters are the oldest around. They’re also the most popular and easiest to find. 

These work because the small grains of sand filter out the debris as the water passes over it. In fact, it filters out particles as small as 20-40 microns. This isn’t the most efficient on the market, but it definitely gets the job done.

Sand filters don’t use just regular ol’ sandbox sand. If you have this type of pump, you’ll fill the tank with silica sand that you can find at pool supply, hardware, or home improvement stores. 

People like these filters because they’re inexpensive and relatively easy to maintain. To clean them, you run a backwash cycle that cleans the buildup off the sand. 

Of course, eventually, you’ll have to replace the sand when it gets too dirty to clean with this method. But that only happens about every 5-7 years. 

DE Filters

DE (or diatomaceous earth) is a substance made from the “fossilized remains of tiny aquatic organisms called diatoms.” 

Weird, right?

And even weirder is the fact that it makes up about 26% of the earth’s crust.

For pools, this substance is used to coat DE filters with little grids or “fingers”. It then grabs onto particles as the water passes over it.

These filters are actually the most efficient filters on the market, removing particles down to 2-3 microns in size. In other words, pools with DE filters are the cleanest around as long as they’re maintained properly.

Speaking of maintaining, these are a little more time-consuming to maintain than other types of filters. Not only do you have to backwash them regularly, but you also have to add replacement DE powder each time you do.

In addition to that, you’ll have to take the filter apart twice a year to clean all the little grids manually.

Cartridge Filters

Cartridge filters use disposable cartridges to filter the water as it passes through. They’re usually made with pleated spun polyester.

This fabric traps debris as small as 5-25 microns as the water passes through. This is a lot better than sand, but not as efficient as DE.

A lot of pool owners prefer these types of filters because they’re so easy to maintain. You only need to take it out and rinse it off about twice a year. And when it gets too dirty to easily clean, you simply toss it and put in a new one. 

The cartridges will run you anywhere from $30 - $100 but they usually last up to 5 years, so they’re pretty economical.

How often should a pool filter be cleaned?

Each type of filter is a little different, but for the most part, it’s a good idea to clean them once a month or every couple of months.

However, if you regularly have a lot of swimmers in the pool or a problem with algae, you’ll probably need to clean it more often. In these cases, you might have to clean them every week or two until everything gets back to normal.

Even though it’s best to just clean these as part of your regular maintenance routine, there are some clear indicators you can look for when it’s time to clean them.

Mainly you should pay close attention to the pressure gauge. Normal pressure for a pool pump is around 10 PSI. When it starts to rise above that number, it means there’s too much junk in the filter and it needs to be cleaned out. 

If it gets a little low, on the other hand, it could mean you have a blockage somewhere. This also might require some cleaning, depending on what and where it is.

How to clean a cartridge pool filter

Supplies:

  • Garden hose

  • High-pressure nozzle

  • Filter cleaner

  • Five-gallon bucket

Since cartridge filters are the easiest to clean, it shouldn’t take you much time at all.  

  1. Turn off your pool pump.

  2. Let the air out of the pump by slowly opening the air valve.

  3. Disconnect the filter and remove the top of it.

  4. Remove the cartridge(s) and check for tears or holes (in case they need to be replaced).

  5. Spray the cartridge down with your nozzle attached to the hose. Be sure to get in between all the pleats and remove all debris.

  6. If this doesn’t get it completely clean, use a filter cleaner. This is usually mixed with water in a bucket so the filter can soak overnight.

  7. Then remove them from the bucket and rinse thoroughly with your high-pressure nozzle.

  8. Replace the filter and all the fittings and turn on your pump.

How to clean a sand pool filter

Cleaning a sand filter requires backwashing, which sounds difficult, but it’s really just a different setting on your filter.

Supplies:

  • Pool hose

  1. Turn the pump off.

  2. Attach the pool hose to the backwash port on the sand filter.

  3. Select “backwash” on the multiport valve handle.

  4. Turn the pump back on and allow the water to rush out of the backwash port and through the backwash hose for a couple of minutes or until the water in the sight glass runs clear.

  5. Turn the pump off again and set the multiport filter valve to “rinse”. 

  6. Turn the pump on again and allow it to run for about a minute.

  7. Finally, switch the pump back off and return to its normal setting. (usually “filter”).

How to clean a D.E. Pool Filter

Cleaning a DE filter is very similar to cleaning a sand filter, but replacing the medium is a bit different.

Supplies: 

  • Pool hose

  • Garden hose

  • High-pressure nozzle

  • DE powder

  • DE scoop

  1. Backwash the filter by following the instructions above for cleaning a sand filter.

  1. Next, make sure the pump is turned off and open the air relief valve.

  2. Remove the drain plug and let the water out of the tank.

  3. Disassemble the DE filter per your manufacturer’s instructions (usually a clamp or bolts).

  4. Take out each grid or “finger” of your filter.

  5. Use a garden hose and high-pressure nozzle to flush out all the DE from the filter and rinse out the tank.

  6. Place the grids back inside the filter.

  7. Prime the pump by allowing some water to fill the strainer basket.

  8. Replace the lid and tighten the clamp or bolts.

  9. Follow your manufacturer’s instructions for adding DE powder to the filter.

Cleaning Pool Filters FAQs

How do I clean a large pool filter?

The steps for cleaning a pool filter are the same no matter what size it is. Larger filters just might require a little assistance and a bit more time.

How do you flush a pool filter?

Some people call backwashing “flushing”. This is pretty accurate since you’re flushing the debris from the filter medium. 

To do this, you can follow the guide for backwashing here:

  1. Turn the pump off.

  2. Attach the pool hose to the backwash port on the sand filter.

  3. Select “backwash” on the multiport valve handle.

  4. Turn the pump back on and allow the water to rush out of the backwash port and through the backwash hose for a couple of minutes or until the water in the sight glass runs clear.

  5. Turn the pump off again and set the multiport filter valve to “rinse”. 

  6. Turn the pump on again and allow it to run for about a minute.

  7. Finally, switch the pump back off and return to its normal setting. (usually “filter”).

What do you soak your pool filter in?

We recommend using a cleaner made specifically for pool filters when they need soaking. But there are a number of homemade solutions you can use, such as dish soap, vinegar, or trisodium phosphate.

How to clean a Hayward or Pentair Pool Filter?

These manufacturers recommend deep cleaning their filters once a year, and there’s a very good video tutorial you can follow here.

What else can I use to clean a pool filter?

Dish soap, vinegar, Trisodium phosphate (TSP), and bleach are all good agents for getting those pool filters clean. Just make sure to mix them all with water at about a 3:1 ration (water being the 3).

For extremely dirty filters, you can use a solution of muriatic acid. But this should only be used in extreme cases, such as algae or calcium buildups.

Conclusion

That’s it! You’re now armed with all the information you need to keep your filters clean and functioning well!

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