How to Clean Your Pool Filter
DE Filters vs. Cartridge Filters vs. Sand Filters
To clean an inground pool filter correctly, first identify which type of filter your pool is equipped with.
Diatomaceous earth (DE) filters have their own pros and cons:
- Provide the highest filtration level, removing particles as tiny as five microns (human hair is around 50-75 microns)
- Most expensive type of pool filter
- Most arduous cleaning and backwashing process (reversing the water flow so it flushes dirt and debris out)
- Should be cleaned at least once a month
The cartridge filter uses spun polyester to clean all the debris from your pool water:
- Available in single element cartridges with one filter or multi-element cartridges
- Lowest levels of cleaning and maintenance required—just take it apart and rinse it off a few times a year with a pool filter cleaning solution!
A sand filter is a tank filled three-fourths of the way with sand or glass media to filter the pool water:
- Traps micro-particles as small as 20 microns
- Cleaning and backwashing process takes just a few minutes
What is the Best Way to Clean a Pool Filter?
The cleaning process is different for each type of filter.
Backwashing is a common technique used to clean DE and sand pool filters. Instead of pushing water through the filter to capture particles, you reverse the process to flush the contaminants out of the filter.
You cannot clean a cartridge filter by backwashing. The only way to remove the pool debris is by taking the cartridge apart and rinsing it thoroughly (only use a cleaning solution if it’s extremely dirty).
Step-by-Step Guides to Cleaning Your Pool Filter
Whether you have a DE, cartridge, or sand filter, learn how to clean a pool filtration system.
How to Clean a DE Filter
- Backwash the filter until the sight glass is clear, then turn off the pump and turn the backwash valve to “filter.”
- Open the air relief valve, take out the drain plug, and let the water drain out of the tank.
- Open the filter tank and give it a thorough rinse, making sure to clean the grids and manifold with a spray nozzle (if your grids are exceptionally dirty, you can use a DE cleaner).
- Check manifold and grids for damage like cracks or tears.
- Place everything back in its original position inside the tank (don’t over tighten the nuts!), lubricate the filter tank’s O-ring, and replace the top of the filter tank.
- Mix up the grid cleaner into a slurry according to directions.
- Fill the strainer housing with water (let some water move through the incoming line), then close the lid.
- Open the pressure relief valve and turn on the pump. Turn off the air valve when you see water coming out.
- Pour the DE cleaner slurry into the pool skimmer, let the pump run for at least 30 minutes.
How to Clean Pool Filter Cartridges
- Turn off your pump and slowly open your air-relief valve to release excess air
- Dismantle the cartridge filter (your user manual will come in handy here!) to get to the cartridge
- Remove each cartridge and examine for damage, then place somewhere safe
- Use a spray nozzle on a hose to remove contaminants, ensuring you get the water spray in between
- If your cartridge is oily or extra grimy, you can soak it in a pool cleaning solution for up to eight hours, make sure to get in between the pleats
- Secure the clean cartridges in place inside the filter and replace the filter lid
- Inspect the O-ring for damage like cracks and tears and replace if need be
- Lubricate the O-ring, turn the system back on, and open the air-relief valve again
- Wait until you have a consistent stream of water coming from the air relief valve, then close it
- Examine the pressure gauge to check that the PSI is in a normal range (if it’s off, you may have put the filter back together incorrectly)
Sand Pool Filter
Before you start, make sure you have the following items:
- Backwash hose
- Sand filter cleaner
- Turn off the pump.
- Set your valve to “backwash.”
- Close your return fittings.
- Place your waste hose where you want the dirty water to flow.
- Turn the pump back on and check if the water in the sight glass is cloudy. (It should be.)
- Run the pump on the”backwash” setting for three to five minutes or until the water in the sight glass looks clear.
- Turn off the pump and the power.
Pool Filter Cleaning Checklist
Download our free step-by-step checklist for cleaning different types of pool filters, including diatomaceous earth (DE) filters, pool filter cartridges and sand filters.
Pool Filter Cleaning FAQs
You should aim to clean your cartridge when needed, depending on your pressure reading. Typically, the recommended cleaning interval is once every 1 to 3 weeks. Beyond that, the best way to determine if you need to clean your pool cartridge filter is by checking the pressure on the gauge. A number between 8 and 10 PSI over what a brand new filter would show means that it’s time to clean it.
You can – and should – clean a DE filter as-needed, with no set time. If your water is cloudy, hazy, or green – it’s time to clean your filter. Pressure is often the best marker to determine when to backwash your filter. If pressure has risen between 8-10 PSI over its benchmark of when you last cleaned it, your filter is due for a fresh cleaning.
Cartridge filters can go up to six months without cleaning, but most will likely need to be rinsed around the three-month mark, depending on pool balance and clarity.
The quality of your pool water, how often you use your pool, and your surrounding environment all play a key role in how often you should clean your filter. However, you can always use the pressure gauge as a benchmark for when you need to clean, regardless of the type of pool filter. If the pressure is 8-10 PSI over its startup (freshly cleaned) level, it’s time to clean it.
Pool owners should aim to replace the sand in the filter every three to five years. However, the longevity of your sand depends on how often you use your pool. The more you use your filter, the shorter the lifespan of the sand. If your water chemistry is balanced, but your pool begins to look cloudy – even after multiple filter cleanings – it’s a sign you may need to replace the sand.
It’s important to inspect your sand filter to know when it may need to be replaced. Look for these signs:
- Cloudy water: This may be a sign that your sand needs to be replaced, your sand filter is clogged, or sand bed is contaminated.
- Dripping multiport valves: Leaky valves aren’t a sand filter problem per se, but they do impact your filter’s effectiveness.
- Sand in your pool: If you have a damaged lateral, It will allow sand to pass through and into the pool in the return lines. Look for sand beneath your return fitting. Sand will come out of the fitting and fall right to the floor.
- Broken valves: Valve failure renders your sand filter virtually useless.
- Split tank: A ruptured tank will need to be replaced. If you see any signs of fracture, turn your filter off immediately.
- The pressure is too high: If your filter isn’t functioning properly, it most likely needs cleaning. Low pressure means less restriction—too low could indicate your return fittings are missing. Low pressure isn’t a problem as long as the flow is there.
No. You should never pressure wash a pool filter cartridge. High levels of pressure can cause damage to the filter, reducing its lifespan. Instead, simply clean a cartridge pool filter with plain water. For oily cartridges, soap and water or pool cleaning solution will do the trick.
You may have heard that you can use vinegar or bleach instead of a pool filter cleaning solution. While this may save you some money, for an effective cleaning, we recommend using an actual filter cleaning solution.
Your pump and skimmer baskets are the first line of defense for keeping your pool clean. Anything that makes it past them will head straight to the pool filter. Follow these steps to clean the skimmer basket:
- Turn off your pump.
- Pull off the skimmer’s lid, pick up the basket and empty out all the debris.
- Give it a good rinse.
- Place it back in position.
- Restart your pump.
The process to clean a pump basket is slightly more involved:If it was in use, turn off the heater and wait 5-10 minutes for it to cool down.
- Close the main drain and skimmer valves.
- Turn off the pump.
- Reach inside to grab the pump basket, then remove the debris inside.
- Rinse off the skimmer basket using a garden hose and examine it for damage.
- Return it to its original location—if your pump basket is a twist-in model, do not over-tighten.
- Check the pump lid and O-ring for signs of wear and tear, and smooth on some petroleum jelly if the O-ring appears dry.
- Return pump lid and O-ring to their original places, then check that the filter valve is set to “filter” position.
- Open the main drain valve and the pool filter’s air relief valve
- Turn the pump and heater back on.
- Open remaining skimmer valves and close the air relief valve only when you see a consistent stream of water coming out of it.
Pool filter cartridges can last up to five years but typically need to be replaced sometime after three. You’ll be able to tell that the filter is not doing its job as effectively if your water takes on a greenish hue or you notice that you need to clean it more frequently than usual. Good maintenance will help extend the life of your pool filter cartridge, so take care to clean it regularly.
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