The DE Filter Replacement Decision

That old DE filter on the pad is doing more than collecting dirt, it is quietly adding hours to your workload and choking your pool’s circulation every time the PSI creeps up. We break down what really happens when a DE grid filter ages out, why the “quickest” replacement can be the most expensive choice over time, and what upgrades actually make a difference for water clarity, flow, and weekly maintenance.

We use a familiar setup like a Pentair FNS Plus as the reference point and compare realistic replacement paths: swapping to another DE filter, moving to a sand filter, stepping up to a quad DE filter, or making the jump to a high-capacity cartridge filter. The biggest takeaway is surface area. Going from a 60 sq ft DE filter to a 500 to 520 sq ft cartridge filter can multiply filtration area many times over, which translates into stronger returns, a healthier spa spillway, fewer flow-related water quality problems, and far fewer filter cleanings. We also cover the practical retrofit details pool service pros care about, like removing the backwash valve, dealing with reversed plumbing, and choosing a cartridge model that fits the same equipment pad footprint.

We also talk safety and compliance: DE dust can be hazardous if inhaled, DE residue can linger around equipment areas for years, and dumping DE into the street or storm drains can lead to fines in places like California. If you want a cleaner pad, simpler cleanings, and steadier circulation, this is the roadmap.

Subscribe for more pool service tactics, share this with a tech who still dreads DE cleanups, and leave a review with your go-to filter upgrade and why.

We walk through the best options when a DE pool filter finally wears out and why the easiest swap is not always the best upgrade. We make the case for a large cartridge filter to boost flow, reduce cleanings, avoid DE mess, and simplify life for both techs and homeowners.
• replacing a worn DE filter with a large cartridge filter for major surface area gains
• why DE filters get inefficient as PSI rises and flow drops
• what improves when circulation stays strong: returns, spillway, heater performance, chemical mixing
• plumbing considerations when converting DE to cartridge, including removing the backwash valve and reversed ports
• why sand filters usually make less sense than cartridges for footprint and efficiency
• when a quad DE filter is a reasonable choice and why it needs a specific backwash setup
• safety and compliance issues around DE dust and disposing of backwash water

Learn more at Swimmy.
If you're interested in a coaching program, you can learn more at PoolGatcoaching.com.

Support the Pool Guy Podcast Show Sponsors! 

HASA  REWARDS App
https://hasa.com/hasa-app

The Bottom Feeder. Save $100 with Code: DVB100
https://store.thebottomfeeder.com/

Try Skimmer FREE for 30 days:
https://getskimmer.com/poolguy 

Get UPA Liability Insurance $64 a month! https://forms.gle/F9YoTWNQ8WnvT4QBA

Transcript

Copy Transcript Copied

When A DE Filter Wears Out

SPEAKER_01 1:05

Hey, welcome to the Pool Guy Podcast Show. In this episode, I'm going to talk to you about when you go to replace your DE type diet and basis earth filter.

SPEAKER_00 1:14

What would be the best choice and the best replacement for a DE pool filter?

Coaching Program For Pool Pros

SPEAKER_00 1:20

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 Swimmy.

Why Cartridge Beats DE Replacement

SPEAKER_01 1:39

And I'll use the Pentair FNS Plus as kind of my default pool filter here for this podcast, so that I'm not mentioning other pool filters, even though there's a lot of the filters out there. I'll just stick with this one because it's easy identifiable. And Pentare is pretty big in my area, so this is the filter that a lot of us run into out there. Let's just say that the filter's 15 years old, it's worn out, the customer is done with it, you're done with it, and you want to get a replacement filter. Well, of course, the easiest thing to do plumbing-wise is just to unscrew the unions and put another FNS plus filter there. Not what I would recommend you do, even though it's the easiest and quickest way of doing things. I think if you have a chance to get rid of the D filter, take that chance and replace it with a good cartridge filter. And this is mainly because the D filter is not there's nothing inherently wrong with the D filter, I should say. And D filters are great filter types. They filter down to the three microns and they're efficient, but they are messy, they are a pain to clean. And if you had an FNS plus filter and you've been cleaning it in your customer's backyard for 10 years, there's gonna be some like DE clay that's gonna be there forever in the planter or wherever you're cleaning it, and D residue, even if you replace it with a cartridge filter, years later you're gonna find DE still back there. And these are messy, they take a long time to clean. And the top manifold filters are especially notorious for really being you know hard to put back together and to maintain if you have a torn grid somewhere, you have to take it apart, look for that tear. Maybe there's a crack in a top manifold. So for me, I would replace it, of course, with a cartridge filter. You're going to maximize the square footage of that cartridge, of the filter with a cartridge filter, I should say, over

Flow Gains From More Filter Area

SPEAKER_01 3:33

D filter. Let's just say you had a 60 square foot FNS plus filter there. If you put in a 500 square foot cartridge filter, you're going to pretty much, you know, 10 times, 8 or 10 times more filtration area is created with a cartridge filter right away. So you're going to increase the flow of the pool. It's going to be much easier to, of course, maintain that filter. Cleaning it is going to be a breeze. You just take it apart, hose off all four cartridges. There's no diatomasis earth mess anywhere. It's going to be a big game changer for you and the customer. And I really think cartridge filters, although you're going to sacrifice a few things that the V filter had over the cartridge filter, and that is that you can't backwash the cartridge filter when you could have easily backwashed FNS Plus filter. However, because of the eight or ten times square footage that you've increased it to, going from 60 square feet to 500 or 520 or 550 square feet, what's going to happen is that you won't need to clean the filter as often or backwash it at all. Usually with the cartridge filter that's 500 square feet or more, you can go six months without cleaning that filter, and the psi or the pressure won't drop one bit. You're not going to have any problems like with the D filter. Once that pressure gauge gets to 30 psi, you notice the spa spillway is not working. Maybe the return jets are weak, the heater's not coming on. It's basically the D filter runs on a different principle. It's a much smaller square footage area. And so the pressure that builds up when it gets dirty is much greater than what would happen in a cartridge filter with the same amount of dirt load. You have 500 square feet of area for that dirt to be dispersed in versus 60 square feet with a D filter. So that alone is going to allow it to last a lot longer between cleanings, and it's going to make it much more efficient and effective as far as flow. I mentioned this before, I had a pool that had a 36 square foot Purex D filter. It was a pretty big pool too, like 20,000, 25,000 gallons. I don't know what the builder was thinking back then. It was okay. The pool had no debris around it. You can keep it pretty clean, and so it wasn't an issue with algae or anything like that or water quality. But when I put in a Pentair 520 square foot cartridge filter, the flow on that pool was so great that I actually had to open up the spa return more to regulate the flow because there was just so much water coming out of the returns from going from a 36 square foot D filter to a 520 square foot cartridge filter. So that of course was pretty tremendous, and you're gonna notice that right away when you go from a small D filter, 60 square foot is relatively small, in my opinion, to a large cartridge filter. It's going to be night and day as far as flow and as far as maintenance of the pool. And it's definitely a win-win.

Why Sand Is Usually A Downgrade

SPEAKER_01 6:40

There's more plumbing required going from a D filter to a cartridge filter, of course. You have to cut out the backwash valve, and the plumbing is actually reversed on the cartridge filter. The end letting out a letter opposite a D filter, so keep that in mind as well. That there's a little bit more plumbing involved when you're going from D to cartridge filter, but it's well worth it, in my opinion, to go from a D to cartridge filter. Now I suppose you can go from a D filter to a sand filter. I haven't seen anyone do that in my area. I wouldn't really recommend that if the cartridge filter is available and, in my opinion, better than a sand filter and better than a D filter. It wouldn't make a lot of sense to go from a D filter to a sand filter. And again, it's something you have an option to do, but the sand filter is going to take up a bigger footprint than where your D filter was. The cartridge filter will fit pretty much directly where the D filter was. So there's an advantage there in your equipment area going from a 520 square foot cartridge filter, let's just say the cleaning clear plus by Penthair, replacing your Penthair FNS Plus. It's going to take up the same footprint as that FNS Plus filter, but internally it's going to give you 10 times more square footage. With a sand filter, they're kind of bubbly, kind of bubba. And so if you're going from a D filter to a sand filter, it may not fit very well in your equipment area. Keep that in mind as well. Yes, they're low maintenance, they're easy to maintain. All you do is backwash them, maybe change the sand out every six or eight years. So it is a low maintenance type filter, but it's not as efficient in my opinion as the cartridge filter for flow and for just a lot of water quality issues than a sand filter. So I would say the cartridge filter is much better, better choice if you had a D filter and you're going from DE, I would go to a cartridge. Now, what about the quad DE filter? Would I recommend that? And I would say in some cases I would recommend it. I like

When A Quad DE Filter Makes Sense

SPEAKER_01 9:07

the quad D filters. Would I go from a 60 square foot D filter to a 60 square foot quad D filter? I probably would if the pool was running fine with a 60 square foot D filter. The quad D filters, in my opinion, are the best D filters out there because they're really easy to clean. They're very much like a cartridge filter. They look like a cartridge basically, but with the DE grid material on it. You still have to use DE in it, dietomaceous earth in it, so you don't really move away from the DE. But you do get a better filter, in my opinion. Now, most of the D filter quad D filters are installed without a backwash valve, and you can't use the same push-pull piston you have on the FNS Plus. It won't work effectively with the quad D filter. Now, Panther does make a specific backwash valve for the quad D filter. You can put that in the place of the piston backwash valve, but the quad D filter is also plumbed in opposite a standard D filter. Keep that in mind that the quad D filter is actually plumbed in opposite of a D filter. That's why you can't use that backwash valve, by the way. Just like you can't use that backwash valve if you change it out and put a cartridge filter in. Because the way the D filter backwash valve works on the FNS Plus is that the water actually is reversed. And so the flow is reversed, and water enters the grids and pushes the dirt off the cartridges from the inside out. And you couldn't do that if you had a quad D filter or a cartridge filter. If you were to open up the backwash valve in that situation, it would not be effective and it could damage the cartridges or or the quad D cartridges inside there. So you need a special backwash valve installed for the quad D filter. However, for some reason, I think it's just the design of the quad D filter, you don't really need to backwash them nearly as often as you would have needed the backwash FNS Plus filter. I don't know exactly what it is. It's probably the design of them. It gives it more area, although it's not a lot more square footage. But I've replaced regular D filters with a backwash valve with quad D filters and not needed to backwash them in six months, just take them apart and clean them. So there was really no need to backwash them. And so the backwash valve was not necessary. And again, you can go from a D filter to a quad D filter. They have 60 square foot, 80 square foot, and 100 square feet quad D filters. And I believe the footprint is still the same for the 100 square foot and a 60 square foot. In fact, the 60 square foot might be a little squatter than the FNS Plus filter. This comes into play because I've had some equipment pads where they actually are covered, and so you have to make sure you have the size filter you can fit in there, and you can't really go too much bigger in a lot of cases. In California, at least, we have really small equipment areas, and going from DE to a quad D filter, you can do that pretty easily because it's the same footprint as the D filter and sometimes even smaller than your existing D filter. Now, cartridge filters, in my opinion, again, are vastly superior over replacing it with another DE filter or even a quad D filter because you move away from the tight dietomaceous earth. I don't like that stuff. I never liked it when I first started pool service. We used to do pools where not only did you have the

DE Mess Safety And City Rules

SPEAKER_01 12:27

DE filter, but you had what was called a separation tank. If you are old like me, you probably have seen these separation tanks. So basically, when you backwash the filter or go to clean it, all the DE would go into this smaller tank with this kind of bag in there or mesh bag. And this would capture all the DE instead of going out into maybe a P trap or going out onto the cement or the yard, it would go into the separation tank. Big pain in the neck. No one liked them. They were kind of effective, but not really effective. Good concept, but it just wasn't working. It doesn't work as well as people thought it did. And so you get away from the diatomaceous earth, which again I mentioned in the beginning, it's like a plague, you know, it's like everywhere. It stays back there for years. I had this pool where I had this equipment area with 2D filters in there, and I could never clean out these this equipment area ever from DE. It was just always there. And DE is a carcinogen, so it's something that if you inhale a lot of the dust, you can get silica in your lungs, and this causes lung disease and possibly lung cancer. So you want to make sure you're careful with diatomaceous earth. So again, with a cartridge filter, none of that has to be even on your mind or nothing, you won't even have to worry about using diatomaceous earth ever again with a cartridge filter. And I did mention the flow issue with the D filter from that to a cartridge filter, and I'm going to hit this again because it's really important to understand that when a D filter starts to get dirty, the PSI there rises, and that affects the flow of the pool, which means that again the return jets are weak, the spa spillway is weak, which leads to poor water quality. You get algae forming in it, the chemicals aren't dispersed properly, and so the D filters, in my opinion, are highly inefficient when they start to get dirty, and it leads to more shocking of the pool, more water quality issues, more maintenance issues. Whereas the cartridge filter, and again, I'm not talking about a single 100 square foot cartridge filter, or even a 200 square foot cartridge filter. I'm talking about larger cartridge filters, except for the Aqua Aqua Star Pipeline filter, which is equivalent in its size to a larger filter. But the larger 400-500 square foot cartridge filters, I currently have a 450 square foot one on my pool, really doesn't affect the flow doesn't get affected by dirt, and it's one of those things where if you can avoid shocking the pool, having water quality issues, brushing algae, it goes a long way in making your day a lot easier out there on your pool route. And maintaining these pools is really easy with a cartridge filter, because then after four to six months, whenever you're scheduled to cleaning, hose off the cartridges, put them back in, and you're you're good to go without having to worry about diatomaceous earth and any kind of mess. You can hose the cartridge filter off anywhere on the grass and the planter because all you're hosing off is dirt. You're not hosing off any diatomaceous earth. So another advantage is that you can clean them on the grass, on the on the cement by a drain in the planter, in the streets in front. You could not clean a D filter in the street here in California in the front yard, by the way. The city will give you a ticket. DE is not supposed to get down into the storm drains, and even backwashing a D filter out into the street will get you a sizable ticket. I remember one time I was cleaning a D filter or backwashing it. I was at this account. I did not know where the DE was going. This was a brand new account, and I figured the builder knew what they were doing, but they apparently didn't, and they actually had the waistline going out basically into the street. And so DE was getting put into the street. And I remember like there was like a city safety worker driving around. There was actually the fire department too driving around looking for the source of this. Unfortunately, they couldn't tell which house it was coming from. You know, people had sprinklers running, there was over water all over the place and the gutters, and it wasn't just the pool that I was backwashing that was draining at. There was other homes too. So they weren't able to isolate which house it came from. But it's a pretty sizable ticket getting D into the street, and it should not have been plumbed directly into the gutter. It should have been plumbed into the sewer line or you know, somewhere more appropriate. And just is to say that a lot of builders aren't putting in D filters anymore because of the regulations. You can't have the wasteland going out to the street. You have to have a going into the sewer or P trap going into the sewer. So a lot of builders are putting in cartridge filters or even sand filters, I guess, and not D filters because of those regulations. So even on a new build, you couldn't get a D filter, and it's much more efficient to have a cartridge filter anyway. As long as you know how to retrofit it, you know, there is some plumbing issues I mentioned, reversing the plumbing, and as far as fitting it where the where the D filter was, should be no problem at all. And to me, it makes it much easier to maintain and clean a cartridge filter. If you have employees, they can clean it much easier than a D filter. And there really isn't a lot of other issues, like for instance, the D filter will leak DE into the pool, and then you have to take it apart, find a torn grid, or maybe a crack manifold, or even the stem O-ring. And it takes a lot of effort sometimes to find where the D is leaking. And for me, eliminating that whole part of the equation, never having to look for a hole in a grid, or looking, you know, putting DE in the skimmer and have it shoot back into the pool, it's kind of like a nightmare situation in a lot of cases. All that's eliminated with a cartridge filter, and just that aspect of it, the headache factor

Wrap Up And Where To Learn More

SPEAKER_01 18:06

of a D filter, the headache of cleaning it, the headache of putting it back together, the headache of using dietomaceous earth makes the cartridge filter much more attractive. If you're looking for other podcasts, you can find us by going to my website, swingpoollearning.com on the banner, click on the podcast icon. There'll be a drop down menu of over 2,000 podcasts for you there. If you're interested in a coaching program, you can learn more at PoolGatcoaching.com. Thanks for listening to this podcast. Have a great week and God bless.