How to Know When a Pool Filter Is Done

Filter problems love to disguise themselves as “chemistry issues” and that’s exactly how pool owners waste weekends and pool pros lose hours. We walk through the real decision that matters: do you simply need new filter media, or is it time to replace the whole filter body because the tank, clamp, or lid is worn out and headed toward failure.

We start with the basics in plain language: what “filter media” means for cartridge, DE, and sand systems, and why each has a different lifespan. Then we get practical with sand filters, including the signs that sand is no longer doing its job (weekly backwashing, rising pressure, poor flow, and water that never quite looks right). If you’re debating a pool filter upgrade, we talk through when a cartridge filter makes sense, when a sand filter is still the better choice in heavy dirt regions, and why large square-foot cartridge filters can deliver better circulation and more consistent filtration.

We also share the real-world replacement schedule that keeps service routes smooth: the three-year strategy for quad cartridges and DE grids, what happens when grids tear and DE leaks back into the pool, and the important exceptions where cost and build quality justify longer intervals. Finally, we cover when replacing the entire filter is the smart move, plus what changes when converting from DE to cartridge (including plumbing considerations and removing backwash hardware).

If you want fewer surprises, cleaner water, and better flow, subscribe, share this with a pool owner or pool tech, and leave a review with the filter type you’re running and the problems you’re seeing.

We break down how to decide between replacing pool filter media and replacing the entire filter, using real service-route triggers like pressure rise, flow loss, and stubborn water clarity issues. We also lay out practical upgrade paths from sand or DE to cartridge so you can reduce mess, improve circulation, and prevent mid-season failures.  
• defining filter media across cartridge, DE and sand systems  
• diagnosing sand filter performance using clarity, flow and backwash frequency  
• weighing sand filter simplicity against water waste and lower filtration  
• why large cartridge filters often outperform sand in everyday use  
• setting a proactive replacement schedule for cartridges and DE grids  
• spotting grid tears and deciding when to replace one grid vs all  
• handling expensive cartridge exceptions and extending lifespan responsibly  
• deciding when an aging filter tank should be replaced for safety and cost  
• planning plumbing changes when converting DE to cartridge  

Are you a pool service pro looking to take your business to the next level? Join the pool guy coaching program. Learn more at swimmingpoollearning.com. Looking for other podcasts, you can go to my website, swimmingprolearning.com on the banner, click on the podcast icon. If you're interested in the coaching program that I offer you can learn more at PoolGuyCoaching.com.  

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Transcript

SPEAKER_00 0:14

Hey, welcome to the Pool Brain Podcast Show. In this episode I'm going to talk to you about pool filter upgrades, when you need a new filter, maybe you just need new elements in the filter. So I'll go over how to decide between either a new filter, which type of filter to put in if you're going that direction, or if your filter just needs some new media in there to kind of renew it and make it just like new. Are you a pool service pro looking to take your business to the next level? Join the pool guy coaching program. Get expert advice, business tips, exclusive content, and get direct support. From me, I'm a 35-year veteran in the industry. Whether you're starting out or scaling up, I've got the tools to help you succeed. Learn more at swimmingpoollearning.com. And I'll start with the filter media, that's what we call it. And this basically is whatever is inside

Welcome And The Upgrade Question

SPEAKER_00 1:03

this particular type of filter you have. Either a cartridge filter has cartridges, a D filter has D has grids in there, and a sand filter has sand in the filter, or maybe glass is an alternate filter media that's in the sand filter. And this is what we refer to the industry as filter media. It's something that I guess works and it does cover all the filter types in a general sense. And I think one thing to note is that each of these have a different lifespan. Actually, cartridge filters and defilters kind of have the same lifespan now. They used to be a lot different when the grids were more robust, but they're

Filter Media Basics By Filter Type

SPEAKER_00 1:45

not made as they used to be made like everything else out there. And the sand filter in the sand has, I guess, somewhat of an indefinite lifespan. And in a lot of cases, if you go to the trouble-free pool form, a lot of people like say never change the sand or never have to. Others recommend changing the sand like every five years, some say every seven years or eight years. Sand filters are a little more difficult to diagnose, I think. But one thing that you can keep in mind with a sand filter is if you're having trouble with the water quality, if you're struggling to keep the clear the pool clear and clean, and it's not a chemistry issue, but it's more of a flow issue and a filter issue. If you're having to backwash that filter every week because the pressure goes up, or if it's just not working effectively, changing the sand at that point would probably be the viable option

Sand Filter Symptoms And Reset Options

SPEAKER_00 2:36

to make sure that you're starting over again and getting and really like resetting that sand filter by changing out the media. Now, before you fill it back up with sand, there's an option for a lot of people with sand filters, and that is to go to a cartridge filter. I think it's a better filter in most cases. The only drawback with the cartridge filter is that you can't backwash it like a sand filter. So if you're in an area where you backwash it often, you may want to stick with the sand filter. But the cartridge filter does have a large square foot footage area. So if you put like a 500 square foot cartridge filter in or a 450 square foot cartridge filter, you're going to get a lot of square footage of cleaning area. So even if they start to get a lot of dirt in in the cartridges, it's still going to be a viable option in an area with a lot of dirt. You just have to clean the filters more often. So if you had a quad cartridge filter and you're in the high desert, you may have to clean those every two or three months. But to me, I just think it's a much better filtration system than sand. But a sand filter does work better in those dirt regions because you can backwash them. You can also vacuum the waste if it gets really bad and there's like a lot of dirt in there. So there are some benefits of the sand filter, and there are some benefits of just changing the sand out whenever that sand filter wears out. But the option would be to go with the cartridge filter if you can get away with that. If it's not too bad of an area, you know, if you're in a normal area and your pool doesn't get a lot of dirt in there, I would say when the sand goes bad, finally at that point, have someone clean the sand out for you, cut out that filter, and put in the cartridge filter. The only time I wouldn't recommend that is in really bad dirt regions where the sand filter is actually pretty effective at that point. Another nice benefit of the sand filter, of course, is that you don't have to take it apart and clean it every three months, six months, you know, every year, and you don't have to replace the cartridges in the sand filter. There are no cartridges, just sand basically. So that's the benefit of the sand filter. It's also pretty easy to use because once the pressure goes from 20 to 30, you simply backwash it for two or three minutes, the pressure drops back down. Of course, you're wasting more water with the sand filter, keep that in mind. But it's one of those things where it may be just simple and easy to use, and that's one of the benefits of the sand filter. It's not the greatest filtration system, but it is simple to use and it is long-lasting, and it is what you would consider very low maintenance because you're not cleaning it, taking it apart, or doing any of that from one

Cartridge Upgrade Pros And Tradeoffs

SPEAKER_00 5:13

season to another or during the season. So that's the great benefit of the sand filter, and I think really the only benefit of a sand filter, in my opinion, besides the fact that you can backwash it, vacuum the waste in really dirt areas. So if you have a cartridge filter or a D filter, how often should you change the media or the cartridges and grids in there? I would say that every three years, if you have a quad type cartridge filter, or if you have a grid D filter, every three years would be optimal to change those out and have new filters put in. Now the only exception would be the Pinter Quad D filters. I find that those quad cartridges last a very long time. I would say I you could probably go four to five years with the quad cartridges. The material is really well made. When the bands start to kind of slide down to the bottom and the pleats kind of separate really wide on those quad type D filters, then I would consider changing them. But they could probably go about five years. If they start cracking on top, of course, change them,

Media Lifespan Rules And Key Exceptions

SPEAKER_00 6:15

but you just have to kind of analyze those a little bit closer, and those have a much longer lifespan. In my opinion, than the grids or the cartridge filters. The danger with the D grids leaving them in there too long is that the pressure will eventually cause one to tear, and then you have a D leak going into the pool, which really affects the water quality. It's also a real pain to take the filter apart, clean all the grids off, and look for the torn grid. Sometimes there's more than one torn grid, and that's when you let the grids go four or five years. You start to get individual grids tearing in the filter. My rule of thumb is if you get a new account and you're cleaning the filter and there's three grids that are torn, that's the point where you replace all the grids. Now, if there's one or two grids that are damaged, I'll just put two new grids in and then I'll wait maybe a year whenever I think that the other ones are going to wear out. But typically, if you have three or more grids that are torn when you get a new account, replace all eight grids. And I go to the three-year mark only because they're not made the way they used to be made. They're not they're not really long-lasting. I don't know if it's the material, the manufacturing, or what it is, but if you've been doing service as long as I have, you know that the old cartridge, the old D filters from you know the early 2000s to 1990s, those grids seem to last like forever. They would get stained and discolored, they'd be like a brownish yellow color, ugly color material, but they would last and they wouldn't tear. And you can probably go eight or nine years with those old grids and they would just be completely discolored and really ugly looking, but they would just be fine. But I find that the grids nowadays, when you get to the four or five year mark, even in one year I've had grids tear, they're just not the same. And so three years would be the furthest you want to go. If you want to push it to four years, you could probably do that. But the three-year mark is good because then if you have cartridge filters, the quad cartridge filters, you have that three-year mark as well. So all your customers are gonna have three years with the media, and then no matter what, how they look, I replace them, and that you really avoid a lot of problems by being proactive and replacing the filter media every three years on your service accounts. Of course, if you have single cartridge filters, you're gonna be replacing those much more often every six months to a year. You're gonna change those out. They don't last a super long time. And one of the things that happens if you're using a single cartridge filter and you're not changing it out as often as you should, you're gonna notice that the filter pressure goes from the clean mark, which maybe would be at 15, and then it goes all the way to 25 within a week or two. You're gonna notice really poor flow, algae, lots of issues. So just change out that cartridge filter more often than you think you need to, and it'll prevent a lot of water quality issues again, because those cart single cartridge filters are picking up a big load there in that pool, and they do need to be changed out much more often than the quad type cartridge filters, with the only exception being the Aquastar pipeline filter. That cartridge is really made to last a long time, and you don't have to change those out every six months or a year, in my opinion. They should last just as long as the quad cartridge type filter, so every three years I would say for the Aquastar pipeline. And I guess I should mention another exception to the three-year rule for cartridge filters, and that would be the large stay right system three filters. I mentioned this before that changing those out is really expensive for the customer. In fact, let me look at the current retail price here. So if you have the 450 square foot one, which is really common in my area of Southern California, you're looking at about 614 Shasta pools, discount pool mark 649, Leslie's pools 1099. You probably want to avoid that one because that's like might as well buy a new filter at that price. That there are some generic ones I think that they make. I don't know if they make the 450 square foot one generic. They may make it, but I know that the 300 square foot one they do make a generic one. Let me see if I can find that one here. Impureline does make a kind of generic 300 square foot one, and that's $400 for that one. So they're pretty expensive. Retail cartridges, you can't really get them too much cheaper at your supplier. They're pretty ex they're pretty expensive cartridges. So I usually go five to seven years with the stay right system 3 cartridges. They seem much more robust, by the way, than your typical cartridge filter. They're just gigantic, and they seem to last a lot longer. So those are the ones that I kind of go longer. A lot of reasons for that is the price point. I I really feel bad charging the customer, you know, $700 for cartridges every three years. And in fact, I know for a fact that they can last a little bit longer than your standard cartridge filters, the quad cartridge filters, and I always go to about the five to seven year mark with those just to give the customer a break. And again, they do last longer than the standard cartridges. So at what point do you actually replace the filter? Now, this is one of those things where it's kind of there's no cut and dry time frame to replace a pool filter. Now, if you're struggling with different parts of the filter, I just did a podcast on problems with the clamp, problems with putting the lid on. And if you do notice that it's really worn out and it could potentially crack eventually, you know, if it's 10 or 12 years old, I would say it's near the end of its lifespan if it hasn't reached it already. And I would definitely replace that filter at that point just to prevent problems later. But if you're having any kind of mechanical problems with it, you know, you can't get the lid on correctly, or the clamp, you have to buy a new clamp. And it's one of those things where it may be more cost effective to get a new filter at that point. And it also may be that you

When To Replace The Whole Filter

SPEAKER_00 12:13

want to change from one filter type to another. I was mentioning with a sand filter, if you're not in a real dirt area, you could go with the cartridge filter, and it's much better. There's of course you lose some of the benefits of the sand filter that I mentioned, but you get a lot of the great benefits of a cartridge filter, better flow, more filtration. All these things are a great benefit of cartridge filters, a larger cartridge filters versus a sand filter. And I would really, without hesitating, replace any sand filter with a cartridge filter. I'd also replace D filters with cartridge filters. Whenever the D filter is wearing out, let's say that you've changed the grids four times already now, since you've had that account like 10 to 12 years, you've had that account, and the customer is getting tired of all the DE building up in their planter, it's really messy. The residue after three weeks is still there on the deck. Customers just get frustrated. Whenever I get a customer complaining about the residue of DE everywhere, even when I'm charging it, sometimes I'll like spill some by the skimmer. And I've had some picky customers like, hey, there's some white powder out here by my pool. Can you come by and clean it? And eventually I'll get a chance to talk to them and I'll tell them, you know, there's actually a better alternative than your filter. Since you have like all cement back here, it's really hard for me to clean the D filter effectively without leaving some mess. And you know, also I would recommend cartridge because it gives you better flow. Why don't we replace your D filter with the cartridge filter? And here's the price of this. And it's really an easy sell sometimes when the customer is tired of the mess of DE, and you know, the planter has this gray, you know, hard gray clay that's just stuck in there forever. It's time to change it out to a cartridge filter. And I don't look back when I change out a D filter the cartridge, by the way. Even though I can't backwash it, to me, it's not a big deal because here in my area, we put in the full size four quad cartridge filters, and then you clean those every six months just like a D filter. And really, there's nothing, there's no reason to backwash them because you're going from let's say a 48 square foot D filter to a 450 square foot cartridge filter. You know, there's no argument they're getting 10 times filtration area, and it stays a lot cleaner, much more better flow, and you're not having to backwash it because there's really no need to backwash it because the cartridge filter has such a large filtration area over a standard D filter. So, yes, the filters don't last forever, and eventually you're gonna have to replace them. Which one you replace them with is your preference. Again, cartridge filters are my preference. It's a lot of Pool Pro's preferences, and if they want a D filter again, I mean, yes, you can do that. And what I would normally do if the customer wants the same D filter, I'll just get him the same D filter because then you have you know everything still lined up for it. You just basically drain it out, take the top off, take all the grids out, undo the union, and then you put the new filter right where the old filter was. Pretty simple installation when you're going from a D filter to a D filter. I don't like doing that, and I would recommend I would always recommend a cartridge filter to the customer, but sometimes the customers do like their D filters for whatever reason. And the old time Pool Pros tend to like D filters, they they do have some benefits. Again, you can backwash them like a sand filter. They are the most efficient filter as far as water clarity, they can filter down to 3 microns, where a cartridge filter does 10 to 20 microns, and a sand filter does 30 to 40 microns as far as filtration. You really can't tell the difference looking at a pool with a D filter and a cartridge filter, in my opinion. And D filters again are a little more efficient, but they have the mess factor, I'll call it, associated with them on the other end of it. And yes, you could backwash them, but again, there's something that if you can get away from dealing with all that, I would definitely go from DE to cartridge any day of the week. So when the when the filters are wearing out on your pool route, really suggest that to your customers when they're you know wanting to get a new filter. It's not a big deal with the plumbing in most cases to do it. Just be aware that the inlet and outlet from DE to DE to cartridge are different and you have to do a little bit more re-plumbing, remove the backwash valve and plumb it in directly. But besides that, to me, a cartridge filter is always going to be a better upgrade. It just kind of use your judgment when it comes to filter time replacement. If the filter looks like it's wearing out, if it's really old, and you know, if it's cracked, of course, then of course replace it. But if it's just looking really tired and you just want to sell the customer a new filter at that point, I would say most filters last 8 to 10 years, 12 to 14 years is really pushing it, but you can get away with it in a lot of cases, and you can get away with it. Sometimes there's some filters you're gonna run into, like the Pentair 2000 series that are like 50 years old on your route, which is pretty amazing. Those stainless steel filters or an old Hayward Titan filter, they pretty much last forever. But I always cut those stainless steel filters out as soon as I can and replace them with a fiberglass filter, just because they're old technology, they're a pain sometimes to clean and put back together, and the parts sometimes are hard to come by for these old stainless steel filters. Looking for other podcasts, you can go to my website, swimmingprolearning.com

Installation Notes And Final Recommendations

SPEAKER_00 17:35

on the banner, click on the podcast icon. There'll be a drop down menu with over 1900 podcasts for you there to listen to at your leisure. If you're interested in the coaching program that I offer you can learn more at PoolGuyCoaching.com. Thanks for listening to this podcast. Have the rest of your week. God bless.