filtering ability of the 3 common pool filter types

[UPSguy]

On the Pool School here and various other sites the DE filter is always listed as 3-5 micron, cartridge filters are usually between 5-15 and then sand coming in even higher particle size. Since these numbers seem fairly consistent no matter where you look, just where did these results come from? Any links to independent tests available?

Being a new pool owner I was taking these numbers as "gospel"
.". What led me to question this was another online vendor with almost the same pool school having their description of Peantair's cartridge filters having the ability to filter to 30 microns. Pentairs own website lists their super duty cartridge in a cartridge having a 20 micron ability.

So, just where did all the filter numbers come from?

 

[JohnT]

Various manufacturers claim different filtering ability. As far as I know there is no independent testing. Hayward claims 10-15. Some sites claim 5-10 microns. Pentair claims 20 or 30 microns, depending on the filter. 5-15 is a general number.

 

[JasonLion]

All filters have a rather blurry line between what they filter out and what they don't filter out. To give an extreme example, any filter will catch a golf ball, but when it comes to particles a couple of microns across any kind of filter will catch some of them but not most. The better filters will catch more, the worse filters less. It is a blurry line and different companies measure it in different ways. Some people rate filters based on the smallest particles they can catch 99.9% of the time, others on what they can catch 50% of the time. Everyone picks a different line as their cutoff.

The ordering, DE is best, sand is worst, cartridges are in-between is not at all controversial. Beyond that there is no reason for the exact details to matter. Any pool filter can get your water sparkling clear transparent and beautiful. A significant number of people can't even detect the difference in the water between the different filter types, though many can. It is a subtile distinction as they are all fairly good and the water quality differences come down to fine details that require close attention to notice. The other differences, mostly connivence and cost, make a much larger difference.

 

[UPSguy]

Thank you for the responses. Sometimes I get hung up on details that may not really matter.

 

[BriceJohnson]

These are all BS marketing claims anyways, that a filter has a "micron rating". That rating has to do with whatever the engineer/marketing people decide to choose for a number based on usually an ASTM first pass filtration efficiency test as well as some other tests, which gives you a % of particles caught for a given size. Now, what % do you define as "filtering" or not?

Another point, ANY filter will start to filter finer particles as it starts to get dirty. Cartridge filters when clean don't necessarily filter all that much better than sand filters. Now once they get a little bit dirty, their performance improves considerably, where as a sand filter is basically constant over the filtering cycle. DE filters blow either of these away on the tests.

I will state that Pentair has finer filtration cartridge media than others on the market, based on our testing (product plug I know, but it IS true).

 

[UPSguy]

These are all BS marketing claims anyways, that a filter has a "micron rating". That rating has to do with whatever the engineer/marketing people decide to choose for a number based on usually an ASTM first pass filtration efficiency test as well as some other tests, which gives you a % of particles caught for a given size. Now, what % do you define as "filtering" or not?

Another point, ANY filter will start to filter finer particles as it starts to get dirty. Cartridge filters when clean don't necessarily filter all that much better than sand filters. Now once they get a little bit dirty, their performance improves considerably, where as a sand filter is basically constant over the filtering cycle. DE filters blow either of these away on the tests.

I will state that Pentair has finer filtration cartridge media than others on the market, based on our testing (product plug I know, but it IS true).

Thank you Brice for this and your PM reply. Since you are with Pentair let me ask you this question trying to make an apples to apples comparision. Could you please compare the 320sq' Clean and Clear plus to the 300sq' system:2 and 300 sq' system:3. These are all your products, does one have a noticeable advantage over the others?

Thank you again.

 

[Isaac-1]

I have to disagree about people being able to tell the difference, I changed over from using a sand filter to a DE filter a couple of years ago, and since doing so it seems everyone comments on how clear the water is. Sure this is comparing an older, but not completely worn out sand filter to a new DE one.

Ike

 

[johnsjets]

I found out from experience that perception plays a large part on how clear one's pool water appears to be. I had a DE filter for a couple of years but got tired of the maintenance headaches and switched back to a sand filter. However, I began using a zeolite filtrate instead of the conventional sand, and to be honest, I couldn't tell the difference in clarity between the two. Unless you have the water professionally tested for solids in solution, I doubt most would likewise be able to tell the difference. Keeping the pool equipment running optimally together with proper water balance, has been my mo to maintaining sparkling clean water.