The Clear Choice: How Cartridge Filters Outshine Sand & DE

Crystal-clear water means more than fine micron ratings; it means steady flow, low pressure spikes, and a filter you can actually live with. We dive into the real-world reasons cartridge filters outperform DE and sand for most pools, from massive surface area that keeps PSI stable to a simple cleaning routine that skips the gray dust and regulatory headaches of diatomaceous earth.

We walk through how pleated media provides 7x the surface area of common DE setups, why that matters for circulation, and how stable flow prevents dead zones, improves skimming, and reduces algae risk. You’ll hear practical comparisons: DE at 3–5 microns, cartridge around 10–20, sand near 40—and why your eye won’t notice the difference between 5 and 15 microns, but your spa spillway will notice the flow. We also cover where sand or DE still makes sense, especially in high-dust regions where backwashing is a lifeline, and for homeowners who need the simplest possible maintenance routine.

If you run a variable speed pump, this conversation is a must. Cartridges pair naturally with higher throughput, keeping performance consistent at elevated speeds and making the most of modern 3 HP total-rated motors. We break down service realities—DE recharging, grid tears, cracked manifolds, and messy burps—versus the straightforward hose-and-go workflow of cartridges. Then we talk replacement cycles, brand recommendations for elements, and why most new builds default to cartridges because of both performance and local DE disposal rules.

• Why cartridge surface area preserves flow and reduces PSI rise
• Micron ratings vs what the human eye can see
• When high-dirt regions may favor sand or DE
• Variable speed pump compatibility and throughput
• Cleaning workflows and mess: DE recharging vs quick cartridge rinse
• Common failure points in DE and sand that cartridges avoid
• Cost and replacement cycles for grids vs cartridges
• Sizing guidance using 420–520 sq ft examples
• Builder trends and local DE disposal rules

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Chapters

• 0:00 Setting The Case For Cartridge
• 3:19 Regional Exceptions And Maintenance Cadence
• 4:52 How Cartridge Filtration Works
• 7:08 Microns, Clarity, And Real-World Results
• 9:13 Cleaning Mess: DE Vs Cartridge
• 12:24 Flow Gains From Larger Surface Area
• 15:34 Pressure Rise, Circulation, And Algae Risk
• 18:09 Variable Speed Pumps And Throughput

Transcript

SPEAKER_00: 1:50

Hey, welcome to the Pool Game Podcast Show. In this episode, I'm gonna go over why I believe a cartridge filter is vastly superior to a D filter and a sand filter, and why your next filter in most circumstances should be a cartridge pool filter. 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. Now I do want to emphasize in most cases, because there is an exception to certain areas and certain pools where I think a Karstra's filter may be inferior to a sand or D filter. And these are areas where you get a lot of dirt. So the high desert, low desert of California, parts of, of course, Arizona and Nevada, where dirt is a big issue. You may want to consider a sand or D filter. However, a cartridge filter is still appropriate for those areas. It's just that you're gonna probably clean them more often than I'm gonna state here in this podcast. So instead of cleaning them every four to six months, you may be cleaning them every two months, depending on how much dirt gets in the pool. And you can't backwash a cartridge filter like a sand or D filter. So you have to kind of use that as your gauge for your area. If you're gonna switch to a cartridge filter, I still think in most areas, 95% of the time, the cartridge filter is much a much better choice. And there are some areas or some circumstances. For instance, if you have maybe an elderly parent that has a pool and you want to get a really easy filter with low maintenance, then I would say a sand filter, even though it's not that efficient, would be the best choice because you just backwash a sand filter whenever the pressure gets too high in it, and you never really take it apart to clean it. So those are the exceptions to the rule of why a cartridge filter is superior. And I'm gonna get into the details now of why I think a cartridge filter should be your go-to filter choice for your pool. Briefly, a cartridge filter works just like the other filters in filtering the water, with some exceptions. It uses a pleated polyester or paper type cartridge. I call it paper because it looks like paper, so a lot of people think that it's made out of paper, but it is a paper type material, it's not a cloth material like a D filter, and it's definitely not just sand in the filter like a sand filter. You can't backwash again the cartridge filter, it's just because of the design of it, it just can't be backwashed, and because of the large surface area of a cartridge filter, there should be no need to backwash it anyway, and it filters down to about 10 to 20 microns to give you an idea of how that fares against a D filter. A D filter does filter down to 3 to 5 microns. Because of the diatomaceous earth that's coating the D filter, this traps a lot more particles down to a smaller micron than a cartridge filter, which uses a polyester paper type material. And then the sand filter traps down to about 40 microns. So the cartridge filter kind of falls into the middle between both of these filters, and you really can't tell the difference between a pool on a D filter and a cartridge filter. And in most cases, you can't really tell a pool that's on a sand filter either, because the human eye can't detect certain micron levels and you can't see dirt past a certain level. And the cartridge filter definitely filters enough for sure. Now I did mention that a D filter uses D powder or diatomaceous earth, I should say, that coats the grids that traps the you know the dirt and the algae and everything else from going back into the pool, and it does trap a smaller micron, but it does have the DE powder that's in the filter, and a cartridge filter does not have anything coating the cartridge, so that's the one primary advantage when you go to clean it, is that it's not going to be as messy as cleaning a D filter. So you're not going to be hosing off your deck three weeks later to get some of that gray dust out of there, and it does make cleaning this very easy. You just take the filter apart, hose off the cartridges, all the dirt comes off, and you put it back in the filter. Whereas a D filter, you hose off the grids, or if you have a quad D filter, the DE cartridges, and then you have to find a safe place to hose it off where the DE is not going to get into everything and eventually turn into a hard gray clay. And you also have to be mindful of cleaning it in the street. Many cities and counties have regulations about DE getting into the sewer system. So cleaning a D filter in front of your house is not something that you can do in most cases legally in cities, and so you have to be kind of mindful of that. Some builders will put a P trap and it'll go directly into the sewer, which you know is fine, I guess, in some circumstances. But most new pool builders will just go in a cartridge filter because of the regulations with the D filter, they won't even put one in. The diatomaceous earth is really messy and you have to recharge it when you clean the filter. And if you've ever cleaned, if you are doing pool service and you've cleaned 40 of these in a month, you get tired of the D filters very very quickly. Because of the square footage of the cartridge filter, even though you can't backwash them, it's not really a drawback. If, for example, I'm just gonna compare a 60 square foot D filter, which is a pretty common size filter here, with a 450 or 420 square foot cartridge filter, which is also a very common size here as well. Now, if you just do basic math, if you take let's say 450 square feet and you divide that by 60 square feet, you have 7.5 times more surface area on a cartridge filter for the dirt than you do have on a D filter, which makes a tremendous difference in flow. Now, if you ever change out a D filter, I had I used this example where I had a pool that was about 25,000 gallons. It had a 36 square foot D filter on there for many many years. It's crazy. And I changed it out to a 520 square foot cartridge filter. The flow was so tremendous because it had one return line and it had a small little spa that I had to adjust the return to where the spa was open more, and you know the return line was just jamming with water coming out of there so fast, and you'll you'll the difference was night and day with the flow between a cartridge filter and a D filter. Because of the larger surface area, you also have to worry too much about the filter pressure going from like with a D filter, typically you're at 20 PSI, and when it starts to get dirty, the D the D starts to get a lot of dirt and different things stuck to it, debris, the psi in the filter starts to go up because there's there's more resistance to the water passing through the grids in a D filter, causing more pressure to build in the tank, causing the gauge to go to go from 20 to maybe 30 psi, which restricts the flow back to the pool. And so if you have you can see this pretty obviously, if you have a spa spillway with a D filter, when the PSI gets to about 30, it's gonna be just dripping over the spillway, and maybe not even the spa may not even be circulating at that point because the flow is so restricted in a D filter from all the dirt being in the filter, and this is one drawback with the diatomissions filter, and in some respects the sand filter will also have a rise in psi as as it starts to get dirty, restricting the flow to the pool, which causes a whole slew of other problems. You know, as the flow slows down, of course the skimmer is not pulling in debris that falls to the bottom, the organic debris uses up some of the chlorine. Since it's not flowing really well, there's some dead spots that develop in the pool, and then algae starts to form. But with the cartridge filter, because you have a superior square footage in most cases, you're not going to have that problem because even if the cartridge filter starts to get dirty, the flow is not restricted because of the extra area that you have over a D filter. And therefore, even with a pool that has a cartridge filter that's just as dirty as a D filter, the flow is not restricted at all, and the PSI and the gauge will still stay at 18 or 20. Sometimes up to the six-month period, we have to clean the filter because of the superior flow of the cartridge filter. The cartridge filter is also designed for the modern variable speed pumps that will have a total three horsepower ability, and so you're going to be able to utilize the full flow of your pool equipment based on, of course, you know, your the dynamics of the plumbing. There's going to be some restriction, but I mentioned the extra flow you get with the cartridge filter because of the square footage. This also translates to translates to better flow with a higher horsepower pump. If you wanted to run your variable speed pump at a higher speed, the cartridge filter has no problem maintaining the flow at the higher speed. We're a D filter, there's a certain limit of flow because of the grids and a diatomaceous earth, and a sand filter actually works better on lower flow. On a higher flow, it doesn't work as well as a cartridge filter, and so the cartridge filter does have that, of course, superiority that with a pool that needs a lot of flow, it does work much better to have a cartridge filter. There are also a lot of things that can not go wrong with a cartridge filter, where with a D filter, a sand filter, you could have some problems with those filters that a cartridge filter will not encounter. Basically, the cartridge filter is just the cartridges. You have a top manifold and a bottom manifold, and then you have an air bleeder inside the filter, and that's the components for the cartridge filter. So rarely will you have a problem with debris leaking back into the pool, and you certainly won't have a problem with diet diatomaceous earth leaking back into the pool covering the bottom with this gray powder. Now, a D filter in retrospect has a few more components, and it does have some fail points that a cartridge filter does not have. For instance, a D filter can get a tear in the grid or it could get a crack in the manifold, and it can even have a stem O-ring that's worn out, and all of this will allow the DE and dirt to pass back into the pool, causing a cloudy gray mess in the pool. And if you think this is not going to happen very often, if you do pool service, you know this happens quite often out there where you have a fill a D filter with a leak of some kind, a tear in the grid, crack top manifold, maybe the grids aren't actually in the manifold correctly. Any number of things can cause diatomaceous earth to leak back into the pool, and this is definitely a problem with a D filter. Another problem is sometimes the pool will hick up DE into the pool either through the main drain or when you're cleaning it, some DE may be in the return line, and then when you start everything back up, diatomaceous earth shoots out back into the pool, causing what I call a DE hiccup basically, or a DE burp, and then you have to clean the pool and take care of that. The cartridge filter does not have that problem, and so you avoid all of that when you have a cartridge filter. You just avoid the whole mess associated with diatomaceous earth recharging the filter, a leak in the filter, all these factors I think are important in your decision to upgrade your filter and which one you would want to get. I would not upgrade a D filter to another D filter, it doesn't make any sense in any stretch of the imagination to put the same filter in. If you're struggling with it, you don't like cleaning it, you know, you have problems with it leaking before. Go with the cartridge filter to eliminate all of those issues. I'd like to touch one more time on the fact that a cartridge filter is much easier to clean a D filter because I think this is an important point that really needs to be emphasized. With the cartridge filter, again, you take the lid off, you take the four cartridges out. If you have a four cartridge filter or a single cartridge out of the filter, you simply hose it off into a drain or maybe onto the grass, and then you put it back together and you're done. A D filter, usually it has a top manifold. You have to sometimes you sometimes you can pull the whole thing out, but it's pretty heavy. Other times you can take the top manifold off and clean the grids. Basically, you're hosing the grids off, checking for any holes in the grids, and then you're cleaning it, making sure that you don't make a mess with the DE, and then you're putting the filter back together, and then you're recharging it, hoping that the DE stays in the filter. So the way I did with a DE filter, when I clean one, I'll take my D scoop and I'll put one scoop in the skimmer, and then I'll stand by the return line and I'll say a little prayer that no DE leaks back into the pool. Because if you do that and you put the DE in the skimmer, and then the white powder shoots out the return line, you have to take the whole filter apart, inspect it, check it again for any kind of rips in the grids, cracks in the manifold, and then do the whole cleaning process again, and then put it back together, put the one scoop of DE in the skimmer, and then hope that it's not gonna shoot back into the pool. So all these are drawbacks with a D filter, of course, and make the cartridge filter superior by default in that case. Now, as far as the filter elements, I don't think there's a huge difference in cost when you replace the grids of a D filter and the cartridge filter, because the way I do it on my pool route is I replace both the D grids and the cartridge filters at the same time. So every three years you're getting all new grids in your D filter, and every three years you're getting all new cartridges if you have a quad type four cartridge filter. Now, if there's a single cartridge, you're changing that more often. So keep that in mind that maybe the costs might not be quite as good with a four cartridge filter as a single cartridge filter if you're changing that single cartridge filter more often over time, but it's not really a cost savings one over the other, so that's kind of like a wash when you're thinking about getting a cartridge filter. You're not gonna save money really with replacing the cartridges. Although there are generic cartridges that are pretty inexpensive, I don't recommend those. I just would recommend going with you know a good brand if you're gonna replace the cartridges, Plico, Filber, Unicell, those are brands that I would replace the cartridges with. And there's a variety of elements or cartridges available for each cartridge filter, which makes it nice to shop around when you're going to get new cartridges. Bottom line, the cartridge filter has superior square footage, it also has superior flow over a D filter and a sand filter, and it's going to be easy to clean. And without a few exceptions, I think a cartridge filter is the next filter type that you should install in your pool if you're thinking about upgrading your equipment. If you're building a pool, more than likely the builder will put in a cartridge filter. If not, I would insist on it. And the cartridge filter, in my opinion, is the best filter type out there. If you're looking for other podcasts, you can go to my website, SonyProLearning.com. On the banner, click on the podcast icon. There'll be a drop-down menu with other podcasts there. And if you're interested in the coaching program, you can learn more at PoolGuyCoaching.com. Thanks for listening to this podcast. Have a rest of your week and God bless.