What filter to choose...cartridge or DE

[ThePoolGuy]

DE all the way baby!!


I really don't have much experience with a cart but I have cleaned one once. It's not a bad deal to do but I really perfer the DE because of how clean it gets the pool. As for the maintence of a DE, it's not that bad...now cleaning one is more work than a cart for sure. Even so, I think it's worth the extra work. You also have to add DE each time you BW but you don't have to BW but like once a month and or if the start pressure is higher than normal. The sand filter would be my next choice after a DE filter. If you choose a DE, check into if you can BW into the drain, I've read some areas get picky about the DE but now sure if it's true or not.

edited: don't you have to clean a cart filter once a week or something like that? A DE is about once a year.

[BigSplash]

Sandfilter with a cup of D.E. medium added to the scimmer after each backwash

[jereece]

I have use a cartridge filter with my 27' AG pool for 6 seasons now. I like it. It provides good filtering. I only need to clean the cartridge about once a month. It takes about 20 minutes to clean with a garden hose. At the end of the season, I clean the filter real good and store it in a box. This way I can bring my filter housing and pump into the garage and store it over the winter. A cartridge lasts me about 3-4 seasons. Years ago I had a sand filter with another pool and did not feel that the filtering was as good. So I am happy with my cartridge.

[waterbear]

First let me say that I favor cartridge filters. Now on to some USEFUL info to help you make a decision. (or my filter choice rant, if you prefer to call it that!)
DE will filter to about 6 microns, Carts to about 20....Not too shabby, IMHO
A PROPERLY SIZED cart is not a lot of maintenance, Hose off the cart once a month (10 minutes), soak it yearly (overnight)
DE needs to be backwashed or broken down to be cleaned....a lot of work to break it down plus you have to replace the water lost by backwashing.
A properly cared for cartridge can last 5 years but they can be pricy to replace. DE powder is cheap.
DE powder can cause silacosis if inhaled....need to be careful with it in dry form.
If you want the cleanest, most polished water you can get in you pool get a DE filter. If you will settle for a close second then a Cart is good.
Probably the WORST filter you can get is an UNDERSIZED cart for you pool. Oversize it a bit.
A dirty cart will actually filter better than a clean one (to a point). It can filter down to about 10 microns, dirty DE just stops filtering. A dirty DE filter will cut your flow rate down and cause your pressure to rise much faster than a dirty cart.

Bottom line is both will perform very well if sized properly. DE is a bit more work, especially when you have to break it down, which should be done yearly or more often, depending on how dirty it gets. If the DE filter allows you to backwash (some don't) then that is an option (but not a good one, IMHO. explanation below)

I don't think backwashing a DE filter is a good idea....Can any DE owners tell me what happens to the grids when you run your filter without DE in it?
The grids get clogged with dirt and covered with organics that stick to them and make the DE stick to the grids and you need to break the filter down and clean the grids. Right DE owners?
NOW, what happend when you backwash? You are forcing the water backwards through the grids.....the grids get clogged and dirty with the same organics! Is it any wonder than when you do break down the filter to clean it the DE is caked together on the grids and the grids are clogged? IMHO, when it is time to clean a DE filter it needs to be broken down and cleaned , not backwashed.
Now on to 'bumping' a DE filter....You knock the layer of dirt that is sittiing on the grids and the DE off the grids so the dirt and DE mix together and then the grids recoated with dirty DE. IMHO, this does not make for good filtration. Dirty DE is dirty DE!
Once again I stress that if you want the clearest water you can get then DE IS the way to go....but there is work involved.
Carts are a close second and the amount of work is much less IF THE CART IS SLIGHTLY OVERSIZED for your pool.
If you want the easiest filter to maintain then you want sand. It filters to about 60 microns which really isn't that shabby and backwashing works well with a sand filter. They still should be broken down about once a year and the sand cleaned and checked for channeling.

In actual practice you wll be happy with any filter you pick..All three types do a good job with different tradeoffs. You just have to decide which one is right for you!

[iardon]

DE filter owner here.... man, now I'm all worried about this silacosis thing.

So... what cartridge filter would you recommend for a 35,000 gallon pool (one pool guy told me it's 40,000) with a 1 hp. pump?

Thanks,

Ilan

[waterbear]

DE filter owner here.... man, now I'm all worried about this silacosis thing.
Just use commen sense and don't breathe the stuff. The risk of silicosis from DE power is very small but also very real. (and so are the dangers of working with muratic acid and chlorine! Just use commen sense!)

So... what cartridge filter would you recommend for a 35,000 gallon pool (one pool guy told me it's 40,000) with a 1 hp. pump?
Cartridge filters have a maximum gpm residential flow rate. You want to be well below that. For commercial pools the maximun flow rate is .375 gpm/sq. ft. of filter area which is much lower than the maximum flow the filter can handle. You want to be closer to that flow rate. You need to calculate the flow rate from your pump based on the performance graph and find the biggest filter that will operate at that flow rate or slighly higher. This will be a much larger filter than if you went by the residential rating. For example, my pool would only need a 75 sq. ft. filter accoring to my pump size and the residential maximum flow rate but my builder put in a 150 sq. ft. filter which my pump can handle fine also (my pump had to be larger because of the spa than if I only had a pool. If I didn't have the spa I would have had a smaller pump and would only have needed a 50 sq. ft. filter, which, in fact, one builder used in a proposal with a separate filter system for the spa when I was shopping for a pool) If he had gone with the smaller one I would have a much shorter filter run time (time between cleanings) than I do and would probably hate my cartridge filter.
Thanks,

Ilan

I know this is a bit confusing but it is the best answer I can give. Sizing a pump and filter is a bit tricky. General rule of thumb for a cart. is get the largest sq. ft. your pump and plumbing can handle efficiently.

[jereece]

DE filter owner here.... man, now I'm all worried about this silacosis thing.

So... what cartridge filter would you recommend for a 35,000 gallon pool (one pool guy told me it's 40,000) with a 1 hp. pump?

Thanks,

Ilan

http://www.intheswim.com/Pool-Filter...e-Pool-Filter/

[waterbear]

http://www.intheswim.com/Pool-Filter...e-Pool-Filter/

Multi cartridge filters such as this one (and the Pentair Clean and Clear Plus) are a chore to clean...you have 4 cartridges, not one! they take longer to break down and assemble also. If you need this large a filter I would go with sand or DE before one of these monsters....just my 2 cents!

[CarlD]

Probably the WORST filter you can get is an UNDERSIZED cart for you pool. Oversize it a bit.

Evan is wrong. The worst filter you can get is an undersized filter of ANY type, Cart, DE or Sand!

If you want the easiest filter to maintain then you want sand. It filters to about 60 microns which really isn't that shabby and backwashing works well with a sand filter. They still should be broken down about once a year and the sand cleaned and checked for channeling.

If you oversize your sand filter and are happy with the performance, this isn't necessary. I would disagree here and say do NOT do this unless you have a problem. Even more, the dirtier the sand is over the years, the finer it will filter--it gets BETTER with age!

In actual practice you wll be happy with any filter you pick..All three types do a good job with different tradeoffs. You just have to decide which one is right for you!

Gee--I thought I said that!

Unfortunately, we don't yet know of any research on the improvement due to adding a little DE to a sand filter. Everyone who has used it has been THRILLED with the results (including me). At night, you easily far less stuff in the water when the underwater lights are on--I'm simply amazed at how clear it now is. All the ease of sand filters, and, apparently, most of the performance of DE filters!

Ah, but if only someone would do some research on the filtering increase...You use FAR less DE in the sand system than you do in the DE. I only backwash every 2 or 3 weeks, and only use about 3/4 of a cup of DE each time--that's about 1/4 to 1/3 of one of those large DE measuring cups!

[waterbear]

I will stick to my guns and say that an undersized cart is probably the worst nightmare....I use the intex pools as a prime example!

As far as cleaning a sand filter..I will also stick to my guns...dirty sand can channel and when it does your filtering perfomance drops down to zilch! Once a year at least stick a hose into the sand and let the water carry the dirt out of it and break up any clumping!

That's what is so great about this forum....we get to disagree with each other!

On a final note....gotta agree that adding DE to a sand filter is a good idea...doesn't work with a cart but I have heard that you can add some of that cellulose based DE replacement to a cart and get the same type of effect. Never tried it so I don't know how well it works.