Pool Filter Cartridges: When to Clean and When to Replace

pool filter cartridges clean or replace?Proper cleaning of your filter cartridges will not only help to keep your pool as clean as possible, but also increase it’s useful life.

Eventually, the cartridge will have to be replaced. Dirt, oils and minerals build up which cleaning won’t remove.

Here are some tips for when/how to clean a pool filter cartridge, and when to pronounce your filter cartridge’s useful life as complete.

When to Clean a Pool Filter Cartridge

when to clean a dirty pool filter cartridgeFilter cartridges should be cleaned whenever the filter pressure gauge increases by about 8 PSI (pounds per square inch) or more above the normal operating pressure, or at least every 6 months assuming your filter is properly sized and you haven’t had any unusually large burden placed on the filter (such as a bad algae bloom or very heavy bather loads). If you notice a change in your water quality, inspect the filter for damage/tears, and a cleaning may be needed.

How to Clean a Pool Filter Cartridge

To properly clean a cartridge you’ll want to first remove any large dirt and debris particles and then soak it in a pool filter cartridge cleaning solution to remove built up oils and scum.

Use a garden hose to remove the larger debris, cleaning between the pleats from top to bottom. The more deeply you clean your pool filter cartridge, the longer it will last. Quickly hosing off it off and putting it back in the tank is not recommended. When you clean your cartridges, give it the full treatment each time.

filter-wand for cleaning cartridge filtersThe pool Filter Wand is a brush that you connect to you garden hose to increase water pressure.  This allows you to easily brush the cartridge and have water flow through at the same time.

filter-flosser to clean pool filter cartridgesThe Filter Flosser is a high pressure cleaning head that you attach to a garden hose to blast dirt and debris out of the crevices in your filter.

Once you’ve removed all of the loose debris, soaking the filter in a filter cleaning solution to remove oils and minerals is the next step. Natural Chemistry’s Filter Perfect or In The Swim’s granular filter cleaner are great options.

filter-perfect for cleaning pool filter cartridgesFilter Perfect is a highly concentrated, natural enzyme cleaning solution. Add 1 liter of Filter Perfect to a bucket of 5 to 10 gallons of water and soak the cartridge for a minimum of 6 hours, preferably overnight. Remove the cartridge from the solution and rinse thoroughly.

filter-clean product from intheswimIn The Swim’s granular filter cleaner has similar dosing instructions, add 1lb. of the filter cleaner to 5 gallons of water; soak for 24 hours, then rinse thoroughly.

They both work well on oils and minerals, but – if your cartridge is clogged with oily residues, use the Filter Perfect, and if you have more of a hard water minerals or metal deposits clogging your cartridge, use our Filter Cleaner product.

Tips for pool filter cartridgesFor best results, allow your cartridge to dry after soaking before placing it back in the filter tank.

A tall kitchen trash can usually is tall enough; if not, flip it over after 6-8 hours to soak both ends of the filter cartridge.

Having replacement cartridges allows you to switch cartridges at cleaning time, so you aren’t without filtering during the cleaning and drying process.

When to Replace a Filter Cartridge

gravestone for Pool F. Cartridge

Generally most people replace their filter cartridges about every 3-5 years, but don’t use the amount of time that has passed as the only determining factor, monitor the performance of your filter. Your time frame may be longer or shorter depending on the demand placed on the cartridge.

There are 3 ways to determine when your filter cartridge has given up the ghost.

First way to determine your filter cartridge needs to be replacedPool filter cartridges need to be cleaned when the pressure gauge rises 8 PSI above normal operating pressure. When the time frame in between this increase in pressure begins to shorten significantly, the filter cartridge probably needs to be replaced.

Keep track of the filter pressure and the date you clean your filter cartridge. When the length of time between cleanings is half of what it used to be, your filter cartridge has reached it’s “half-life”, and it’s time to replace.

Second way to determine that your pool filter cartridge needs to be replacedAnother way to determine if your filter cartridge is terminally ill, is when you notice that the water stays cloudy or green despite proper chemical balance, or that you have to run your filter longer or use more sanitizer, to achieve clean and clear pool water.

Clean the cartridge first, but if the problem doesn’t clear up in a few days, the cartridge is probably unable to filter the water as effectively as it once did. Time for a new one.

3rd way to know when it's time to replace your pool filter cartridgeThe third way of determining cartridge mortality is to inspect it thoroughly every time you clean it, looking for rips or tears in the fabric. Damage to the filter will reduce the potential for sufficient filtering. If you have tears, or rips in the fabric, or if there are cracks in the end of the cartridge; it needs to be replaced.

In The Swim carries hundreds of replacement pool cartridges. Our filter cartridge search tool allows you to quickly find your cartridge by part number, size or filter manufacturer.

Need help finding a replacement cartridge, or have any questions about how to care for an aging filter cartridge? Give a call to 1-800-288-7946!


Jackie Wolski
InTheSwim Staff Blogger



Pool Filter Cartridges: When to Clean and When to Replace — 7 Comments


    • Hi, filters that become crushed from pressure could be a result of a return side valve (after the filter) being closed suddenly, blocking water flow and creating a water hammer effect inside of the tank. This could also happen if return side pipes or check valves were clogged, or if pool returns were plugged, and the pump started. It could also be caused from a replacement pump, which is larger and too powerful for the filter design flow rate. I suppose if the fabric becomes extremely clogged with heavy amounts of oils or scale, very heavy amounts, it could also cause collapse or splitting of the end caps.

  2. I’ve noticed small little pin holes on one end of the cartridges, does it matter if they go at the top or bottom when I’m reassembling? There only on one end.

    • Hi Cajan, I’m not familiar with that cartridge, but I would suspect they would go on the bottom, where the manifold collector sits. If your manifold connector sits on top however, face the holes up. My theory is that the holes assist in allowing water to exit the cartridge (most of it is through the center hole though), and into the collector. If your filter collector only fits inside of the center hole and doesn’t cover the entire diameter (and the small holes), then I would think that these holes may be for air release / air relief for trapped air. In such case, facing holes upward would allow for the air to escape. Hope that makes sense!

  3. I bought a pool pump and it has a strainer. Can I replace the strainer with a filter cartridge and run the pump? I have a small 1750 gallon pool. The filter cartridge pump was not working so I bought this pump with a strainer. I’m just hoping I can use a filter cartridge. If not, what do I need?

    • Hi Mike, the larger pump will likely be too powerful for the small filter that you have now. Depending on the size and flow rates that the pump produces, you would select a filter that can handle the water flow. If you identify the pump, you can look at the associated Flow Curve for that pump, and assuming a small amount of resistance for your piping and filter, you can approximate the top end flow of your pump, then you can select a filter whose ‘Design Flow Rate’ matches the flow rates of the pump. In answer to your question, you can’t really remove the strainer and attach a filter to the pump, having a strainer is a good thing, but most pumps are designed to push water into filters, not pull water through them, under suction.

  4. I have noticed that our pool has been turning a light green this past week. It was awesome to learn that one can Use a garden hose to remove the larger debris, cleaning between the pleats from top to bottom. I am no professional so I will be sure to leave it to one to help my pool water not turn green!

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