Sand Filter and Cartridge Filter Owners Please Advise

[amati5]

So I am getting rid of my Purex DE filter because I can't buy the part any more. I read conflicting info about the cleaning process of the cartridge elements. The manual and most people say it's simple as just hose down with a garden hose. But there are also people say it's a nightmare to hose it down, soak with chemical and rinse and wait until it dry. So my question is which way is usually done at what point do you need to soak in chemical and how ofter do you do that? Also, why does it have to be dried before reinstall.

And for sand filter owner, how long you do let the backwash process run. Water is expensive in my area.

My goal is to reduce maintenance to the minimum.

Thanks

[aylad]

Hi, and welcome to the forum!!

I'll let some of the cart filter folks comment on your cartridge questions, but I can say from a sand filter owner standpoint, sand filters are pretty much non-maintenance, except for an occasional backwash. I don't close my pool over the winter, so backwashing and occasional replacing of the spider gasket is the ONLY maintenance I've had to do. You backwash the filter when your pressure rises 6-8 psi over it's "clean" pressure. While actually backwashing the water, it needs to run until the water in the sight glass clears up, usually 2-3 minutes. Then you switch it to "rinse" to rinse the stuff remaining in the pipes out, which takes about another 45 seconds to 1 minute. Then you switch back to "filter" and it's all done!

If you ever have to fight algae blooms, a sand filter will be much easier to deal with than a cartridge. Also, our other 3 mods, who also have sand filters, use a handful of DE in their filters to actually give the sand filter the ability to filter as well as a DE filter.

[Watermom]

I agree with Jan. Sand filters have the easiest maintenance. I don't even backwash as long as Jan does. Probably more like a minute and a half and a 30 second rinse. Can't get any easier than that!

[PoolDoc]

The keys to good sand filter performance are (1) correct filter sand -- small grains, with no superfine particles and (2) correct size. Optimal filter size is ONE size larger than recommended for in-ground pools and TWO sizes larger than recommended for above ground pools.

Ben

[waterbear]

Personally, I love carts and have one myself. They filter almost as well as DE. As far as maintenance goes, it really depends on whether the filter is sized right. Most carts have historically been undersized for the the pools they are on and needed frequent cleanings, sometimes as often as weekly! If the cart is sized correctly it should only need to be cleaned every 3 to 6 months (or possibly only once a season if the pool is not open year 'round.). FWIW, I can run my cart for a year without cleaning and still not have more than about a 3 psi increase in pressure (cleaning is required when pressure rises about 8-10 psi or at least once a year, whichever comes first). FWIW, a "dirty" cart actually filters better than a clean one so you don't want to clean it TOO often.
Soaking is really just once or maybe twice a year, depending on the organic load of your pool. The trick is to have two carts (or set of carts for a multi cart filter) and to swap them out at each cleaning. With proper care the carts will last 5 years or more. To clean then get a 3 dollar short, small bore brass garden hose nozzle. Works better than the expensive cleaning wands and gadgets. As far as sizing goes, what PoolDoc said for sand also can be applied to carts. Personally, I like to look at the commercial sizing instead of the residential sizing but that is probably overkill.

As far as parts for your Purex DE, Pentair owns the Purex name and many of the filters that were manufactured under the Purex name are still in production under the Pentair name. DE is still going to be the best water filtration you can get. FWIW, breaking down a DE filter is more work than cleaning a cart in my opinion.

[johninmartinez]

Amati, I've been a pool owner (with a cartridge filter) for about a year now. I wouldn't say it's a nightmare at all to hose down the filter (it usually doesn't even need it, it stays pretty clean). But one thing to consider with a cartridge filter is this--are you healthy, with a good strong back? When it comes time to clean the cartridge (or at least to check it to see if it needs cleaning), you unlock and remove the top of the housing, and then you have to reach down into the housing and pull up the wet, heavy cartridge, straight up and out of the housing. And that's while you're leaning over, so you can reach down into it. I'm fairly short and it is hard on my back to do this. Aside from that one concern, the actual maintenance of it is practically nil. I pull it out and check it roughly every three or four months (I live in California, we don't have winter here, we just have summer and not-so-summer). And usually it's clean as a whistle. If it isn't, I just hose it down. I don't do any chemical soaking. It's been very low maintenance. Hope this helps.

[CarlD]

While we mods are all sand-filter users and Waterbear and Chem_Geek (I believe) are cart users, and many others are DE users, ALL will give extremely good performance if sized and maintained correctly.

Carts are like eating steamed Blue Crabs in Maryland. If you figure out the "trick" to using carts, as 'Bear and 'Geek have done, they are very easy and even preferable. If you don't, they are painful and messy and you'll curse the day you got one.

Just like "picking" crabs. Once someone showed us the CORRECT way to eat Blue Crabs, it's easy and delicious. Until then, it's slow, messy, painful, and takes a long time to get enough crab to fill you up.

What's great about sand filters is that if sized correctly they have the easiest learning curve. There's no "trick" and they aren't complicated. Dump a little DE in the skimmer, and add a skimmer sock (both low-cost items), and you'll be hard-pressed to find a difference between sand and DE or sand and a cart.

But a properly sized and operated DE filter is still the Gold Standard for how filters should perform. People who have them and know them, love them and wouldn't have anything else. My dad had a DE for 20+ years.

But back to my original point: All three will perform admirably if sized correctly and maintained properly.

Carl

[PoolDoc]

if sized and maintained correctly

. . . and that rarely happens on AG pools, especially, with AG pool sand filters.

Undersized DE and cartridge filters still filter effectively, but just have very short (maybe, very very short) filter runs. Undersized sand filter do not filter effectively, and result in cloudy pools that won't clear up. Undersized or dirty filter cartridges, when coupled with high head (high pressure capable pumps, which include most inground pumps) can collapse, though this tends to be more of a problem on heavily used commercial pools (like the ones I've serviced) than on residential pools.

[CarlD]

So follow Ben's rule: If they recommend a certain size filter for a given pump, go up one size for IG pools and up two sizes for AGs. So, if they recommend a 150# sand filter, on an IG pool, get a 200#. On an AG pool get a 250# filter.
(there are exceptions: My pool is technically AG, but so similar to an IG and uses an IG pump that I only went from the "recommended" 150# sand filter to a 200# sand filter with no problems as I wind up 9 years with it. But recently I did some new calculations and realized that I had no problems because my filter is just over the limit of an adequate filter for my setting. It's ALMOST too small, but "almost", as the saying goes, only counts if you are tossing horse shoes or hand grenades.)

Carl

[PoolDoc]

So, if they recommend a 150# sand filter, on an IG pool, get a 200#. On an AG pool get a 250# filter.

Actually, Carl, that wasn't quite how I meant it.

What actually happens is that the 'recommended' filter size for, say a 20,000 gallon IG pool, is a 22" filter (at 15+ gpm/sft). But, due to some games the industry played with the NSF, the 'recommended' size for a 20K gal AG pool (at the 'rigged' standard of 25 gpm/sft) is about an 18" filter.

But, what you NEED for either pool is a 24" filter, which gives you about 13 gpm/sft.