Sand vs DE vs Cartridge vs reality

cj133

Well-known member
May 6, 2018
214
NJ
I understand there's going be all kinds of opinions, facts and bias on this subject. But.

I've had an argu.............discussion with a close friend several times and I wanted some outside opinions on the matter.

My friend swears by his DE filter. I've always used sand filters. That's fine, but this has really had me wondering because my friend is usually right when it comes to things like this. But, like all of us he's not perfect.

I keep showing my friend how clean my water is and his response is that I'm filtering clean water and to get back to him after I open the pool next spring.
I don't understand how I'm filtering clean water if the system has been in use for several months outside with a lot of people using the pool and all of the trees and plants around? Surely there's been a ton of pollen and dirt landing in the water. Not to mention all of the dirty feet etc. I've got a tree covering half of the pool (it's fun.......).

Is my friend's response valid, or baloney?

I rely on chlorine to keep algae etc in check, not my filter. No? Even if you filter it out of the pool, it's still living in the filter.
If I understood correctly, his claims are as the water gets older and older, it's going to become more and more cloudy. I don't recall ever seeing this with a sand filter.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Well, first let's remember that filter are designed to do just that - filter. They do not sanitize. So chlorine is a must to keep the water sanitized and prevent algae from trying to grow. The age of water is of no consequence which is why we dismiss those who speak of replacing water periodically unless it's to lower CYA and/or CH. As chlorine sanitizes the water, remaining items (oils, hair, grass, dirt, etc) eventually make their way to the filter. It's a joint-effort .... chlorine to sanitize and break-down organic material, and filters to collect the residual items. DE filters do have an advantage in the quality of filtration provided, but that's about it. All 3 types are very reliable, but both chemistry and filtration are required.
ABCs of Pool Water Chemistry
 
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cj133

Well-known member
May 6, 2018
214
NJ
Well, first let's remember that filter are designed to do just that - filter. They do not sanitize. So chlorine is a must to keep the water sanitized and prevent algae from trying to grow. The age of water is of no consequence which is why we dismiss those who speak of replacing water periodically unless it's to lower CYA and/or CH. As chlorine sanitizes the water, remaining items (oils, hair, grass, dirt, etc) eventually make their way to the filter. It's a joint-effort .... chlorine to sanitize and break-down organic material, and filters to collect the residual items. DE filters do have an advantage in the quality of filtration provided, but that's about it. All 3 types are very reliable, but both chemistry and filtration are required.
ABCs of Pool Water Chemistry
Speaking of oils.........
I had a large group of people swimming with sun screen on and I bought those fuzzy balls to absorb the oils.
Maybe it's my imagination, but it seemed to work far better just draining some water via the skimmer alone. I assumed it would primarily skim oils from the top and it sure seemed to work.
 

Divin Dave

TFP Expert
LifeTime Supporter
Oct 2, 2013
5,626
Longview, Texas
Differences in maintenance aside, the only difference in the context of the discussion is the size of the particles that are claimed to be filtered. Sand, about 20 microns, Cartridge, 10 and DE 5.

If you only go by the numbers claimed, then DE has to be the winner based purely upon that.

The reality is, The clarity of the water is due more to the maintenance of it, and keeping it free of algae and bather load dirt and whatever the wind might blow in. Your pool is a perfect example of that and is exactly what TFP is all about. Filter properly, and maintain the chemical balance.

And water will not get cloudier with age because the filter is filtering out all of that stuff along with FC doing it's thing.

And actually, sand filters work a bit better if they are a little bit dirty because then the space between the sand grains is reduced in size, thus trapping smaller particles.
 
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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Speaking of oils.........
I had a large group of people swimming with sun screen on and I bought those fuzzy balls to absorb the oils.
Maybe it's my imagination, but it seemed to work far better just draining some water via the skimmer alone. I assumed it would primarily skim oils from the top and it sure seemed to work.
Great! :goodjob: I've not had to use them, but I've seen others comment on their benefits as well.
 
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Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,214
Bedford, TX
133,

Simply put, you friend is wrong and you and Texas Splash are correct.. Your filter is not there to prevent algae...

To give your friend a tiny bit of credit, a DE filter will clean a green pool slightly faster than a sand filter, but it is a "lot" more work to use when the pool is green. And you have to kill the algae first anyway..

Thanks,

Jim R.
 
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markayash

Gold Supporter
Mar 21, 2016
550
Marrietta Ga
Other then having to remove and clean them a few times a year I like my cartridge filter. I learned from the 1st purchase ( the hard way ) to buy big as you can afford and have space for and use hair nets on skimmers.
 
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cj133

Well-known member
May 6, 2018
214
NJ
Other then having to remove and clean them a few times a year I like my cartridge filter. I learned from the 1st purchase ( the hard way ) to buy big as you can afford and have space for and use hair nets on skimmers.
I have nothing more than the supplied basket in my skimmer.
Though I think the rule to buy as big as you can applies to all filter types, especially sand due to backpressure.
 

markayash

Gold Supporter
Mar 21, 2016
550
Marrietta Ga
I have nothing more than the supplied basket in my skimmer.
Though I think the rule to buy as big as you can applies to all filter types, especially sand due to backpressure.
The hairnet catches a lot of junk for me, but i have a lot of tree poop. I never thought they would help even though the previous owner highly recommend them ( 15 years aog, just started using them this year ) but they do. We had a heavy rain Monday and they were caked with what looked like yellow pollen.
 

cj133

Well-known member
May 6, 2018
214
NJ
The hairnet catches a lot of junk for me, but i have a lot of tree poop. I never thought they would help even though the previous owner highly recommend them ( 15 years aog, just started using them this year ) but they do. We had a heavy rain Monday and they were caked with what looked like yellow pollen.

I think this is one of the ways I'm spoiled by using a sand filter.
I don't really care what goes in there because I backwash it and the stuff just disappears. I never even know about it.

It also seems like I end up backwashing far more often than necessary just to get rid of excess rain water.

Of course, I'm betting having organic stuff in the filter does use chlorine, so that's a negative...........
 
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Cowclops

New member
Aug 15, 2019
1
NY
CJ133's friend here buzzing in for fun - everything you guys said are right, I just wanted to clarify what my thinking was. If you put tap water in a pool and keep the filter running and keep it chlorinated, its no miracle that it will stay clean. My actual off the cuff suggestion was "Cover it for the winter and when you go to open it, check how clean it gets it after its had 7 months of no filtration or chlorination." I bet a DE gets it cleaner and does it faster, BUT I also don't think a sand filter is incapable of (in tandem with chlorine) keeping a pool safe to swim in.

Everything you guys said is right - this has nothing to do with water age and the only reason I've found to turn over water is because of accumulated CYA (which won't be a problem if you're using liquid chlorine instead of tri chlor tablets anyway). Mostly, the original point was that its easier to keep clean water clean, lets see how it looks after its experienced a winter. Whether 20u filtering or 5u filtering is important enough to make a difference is something I'll admit I don't have an answer to - I was 5 years old when my parents bought a DE filter in the house I grew up in, and when I bought my own house the existing pool had an existing DE filter, so thats just what i've experienced. From a price standpoint I've only ever had to pay $30 or so for a bag of DE every couple years, since one is good for a couple summers easily, so it doesn't come up as a major expense compared to other things like chlorine or the electricity to run the pump.
 
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ZcottD

Well-known member
Jun 23, 2017
152
Connecticut
Personally I look at cartridge filters as the perfect solution. Easier to clean and no adding media. Lots of debris getting in during winter, or being left through winter that is under 20u shouldn't be an issue if the pool is opened before it gets too warm.

When my DE filter breaks I'll reward myself with a cartridge filter and never have to deal with DE.
 

mguzzy

Well-known member
Jul 8, 2015
721
OV, CA
My engineering brain has wondered if anybody has ever done dual filters..Either a sand to catch 90% and a cartridge to get the fine stuff..
I actually tried one of these several years ago and didn't seem to do much. But not sure I used it correct, I had it mounted on top of my pump going out.
CircuPool® TJ-16 Typhoon Cyclonic Pre-Filter for Swimming Pools. No Cartridge, No Sand, No DE media
Interesting thread...."Cleaning clean water" has to be the quote of the day!

Yes I've dealt with multiple filtration processes that were staged to remove progressively finer particulates... but it wasn't a pool, it was in a lab set up in a third world rural setting. The last stage was a reverse osmosis filter so we had deionized water for experiments... The other water distillation apparatus produced a sterile liquid that was something not entirely unlike tequila. :p
 
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mguzzy

Well-known member
Jul 8, 2015
721
OV, CA
I'm a cartridge guy... replaced the original DE when it was 15 years old... I just got tired of having to deal with another bag of powder to add to the pool. I usually rinse off my cartridges twice a year.. once at the end of the season and again at the beginning.. I've replaced them once, after about 10 years. There is my boring post without the alcoholic reference.
 

markayash

Gold Supporter
Mar 21, 2016
550
Marrietta Ga
One last note, when I had Iron Jack's told me to add a bag of Jacks filter fiber to my filter and it makes it similar to A DE? But it did trap a lot of rust looking Crud I assumed was Iron. Today I still add a 1/4 bag after each cleaning