Sand Filter or Cartridge?? Which is better?

[Poconos]

Check this thread. I made comments about adding DE to a sand filter.

http://www.poolforum.com/pf2/showthr...ht=%28ajs-1%29

Al

[waterbear]

I guess I will get into the mix. (these are just my thoughts on the matter, folks! Don't get too bent out of shape if you disagree with me! As Al and Dave indicated this is and probably always will be an endless debate!
I like cartridges because, IMHO, the are easier than DE to maintain and give almost as polished a water quality (DE filters to about 5 microns and cartride to about 20). Sand will filter to about 60 microns so it will never get the water as polished as the previous two but it is probably the easiest to care fore. I have had cartridge filters on a portable hot tub, my current pool/spa combo, and on numerous aquariums (talk about a gunked up cartridge...probably worse than Biguinide "goo"!)
I have found that a quick hosing BEFORE the pressure climbs up 10 psi as recommended greatly extends the life of the cartridge, I hose mine off about once a month and the whole process takes about 10 minues including cleaning the skimmer basket in the pump!
The cartridge does need cleaning (soaking) when a lot of organics build up on it. I have been doing a bit of reseach on it and have found that many OEM replacement manufacturerer's recommend soaking in TSP and water and one Austrailian spa equipment company recommomds soaking in a bleach solution (which is also what the aquarium filter manufacterers recommend...btw one of the largest manufactuers of aquarium cartrdige filters is Pentair! The frequency of soaking depends on the bioload (scum, oil, etc.)the filter is filtering My spa used to need it about once a year and my aquariums maybe every 4 months,
If there are any scale deposits then you need to soak in an acid bath to fizz them away.
Now if this sounds like a lot of work then just break down, clean, and reassemble a DE filter!. Yes, it is easy to 'bump' them but all you have done is mixed the dirt and the DE and the filter medium is still dirty and likely to restrict water flow. You can backwash them, but IMHO, not a good idea since you have no idea how much DE you flushed out so you really don't know how much to put back in. You run the risk of either not having enough DE in the filter and plugging the laterals with dirt or having too much DE which, in a worse case,can mean having to take the filter apart and literally chop out the hardened DE inside the filter! I admit that is a relatively rare occurance but it does happen!. IMHO, if a DE filter is dirty (and they get dirty enough to restrict the flow through them pretty fast!) it should be broken down and cleaned.
If you don't care about the work involve then DE WILL give you the cleanest water you can get! I am personally a bit too lazy for that and my brother has a DE filter so I have some first hand experience with them too.
(have used them in aquariums also. basically the same on a smaller scale)
Sand is easiest to maintain, Backwashing is very effective, but they are the least effecient of the 3 types of filters at polishing the water. To me a big drawback!
I guess what it all boils down to is to weigh the pros and cons of each type and see what you are willing to put up with!
I opted for almost DE water quality and more work than sand but less than DE and don't mind the expense of replacing the cartridge about every 5 years. I also have the most experience with cartridge filters so I am comfortable with them. I know how they will perform and I know what I need to do to keep them happy!

[CarlD]

I AM surprised...if you backwash your DE filter until the sight glass is clear, then you know you probably have no DE in it. So you add DE, leaving some "room" in case there is some left, until the pressure is where it's supposed to be...and you're done.

And I'm a sand filter guy.

I increase the sand filtering effectiveness several ways:
1) I have a filter clearly rated for a higher capacity than my pump.
2) I have a 2 speed pump I run on "low" most of the time--this increases the difference between the pump and filter and filter is more effective.
3) I add a cup of DE powder after I backwash, enough to raise pressure 4-5 #, no more (see Poconos) which catches more fine stuff.
4) I use "skimmer socks" in my skimmer to catch a portion of the fine stuff there.
5) I run my Dolphin overnight once a week. The Dolphin has as fine, if not finer, a filtering as a DE. It's high-flow, and runs for 8 hours as it's vacuuming, "polishing" the water.
6) I wear out-of-focus glasses so everything is fuzzy and I can't see if the water isn't perfectly clear!

[waterbear]

I AM surprised...if you backwash your DE filter until the sight glass is clear, then you know you probably have no DE in it. So you add DE, leaving some "room" in case there is some left, until the pressure is where it's supposed to be...and you're done.

In a perfect world, yes. DE can have a tendancy to "cake" (for want of a better word) on the grids and even if the sight glass looks clear it is possible for there to be quite a bit of DE left in the filter. You add your DE and leave some 'room' but the filter only lost a little of its DE powder. You have now overfilled. Might not show up on the pressure gauge at first. Do this a few times and you now have a MAJOR filter cleaning to do. This scenerio can happen and does. If you have ever had to chip away at the hardened mass of DE that can occur you certainly don't want to do it more than once!

That is why I feel it is better to tear down rather than backwash a DE. You really don't have any control of knowing how much DE is leaving the filter and therefore how much you REALLY need to put back in.
Bumping is really just being lazy, Mixing the DE with the dirt and crud collected and then redepositing it on the grids is NOT the way to give you good filtration. When the filter media is dirty it needs to be cleaned!
Like I said, just my opinion!

[KurtV]

I'm surprised no has mentioned one of the other favorites in this never-ending debate: Sand filter with zeolite filter medium. The ease of maintening a sand filter with a filtering capability that's better than a cartridge and maybe even better than DE. Can't be beat, right?

(Patiently awaiting post describing arduous zeolite "renewal" procedure that must be performed annually but that no one who actually has this system seems to worry about.)

[waterbear]

I'm surprised no has mentioned one of the other favorites in this never-ending debate: Sand filter with zeolite filter medium. The ease of maintening a sand filter with a filtering capability that's better than a cartridge and maybe even better than DE. Can't be beat, right?
If you really believe all the manufacturer's hype then PLEASE come into the pool store where I work part time and let me sell you some dual action Pace 3" tri-chlor that will keep algae from your pool and make your life simpler along with some sodium hydrogen carbonate for adjusting your TA ...it's better for your pool than baking soda! (those comments ARE 'tounge in cheek'!)
(Patiently awaiting post describing arduous zeolite "renewal" procedure that must be performed annually but that no one who actually has this system seems to worry about.)

Zeolite is great for ammonia scavaging and will probably help to keep choramines down (if you are not using a SWG) but I don't believe it's filtering abiltiy is going to be much better than sand. Yes, it is porous like DE and the pores have a small micron size but the grains are about the same as sand; and water (and the dirt in it) is going to take the 'path of least resistance' which means it will go around the zeolite grains and not through it. DE on the other hand, has a very tiny particle size and when the slurry of DE and water coats the grid, even though the coating is not that thick it is made of of layers and layers of DE the path of least resistance will be throught the porous DE which is what makes it such an excellent filter medium. Even if the water passed around the DE grain it is so tiny that the space between grains is extremely small also.
Actually,I have read through Zeobrites regeneration instructions on their website and they are really no worse than sand cleaning or cartridge soaking (which many cartridge and sand owners don't worry about either!) and is probably only a yearly procedure also. The biggest difference between zeolite and sand its that while sand is only a mechanical filter medium, zeolite is both a mechanical AND chemical filter medium. People have been using it in fresh water aquariums for years now for these very reasons.

[gordyjamz]

Ok here's my opinion so far reguarding sand. If you don't minda slight haze to your water, I suppose its ok. I'm looking to buy a cartridge. Why you ask, I'll tell ya. We bought our house last year with this pool already here. after two weeks the filter was leaking from the backwash pipe. Needed a new spider gasket. Only 12 bucks at the pool store. OK So I put a new one in, worked fine for the rest of the season. This year it was fine till a few days ago. Guess what its leaking again. It's a hayward swimpro. The guy who sold me the house said he just replaced the sand the year prior(2004). Everyone says the sand should be good for up to 6 years? Well I don't know what to believe. water's hazy. I must say I think i fell for something, because common sense told me " how can water be filtered from sand?" I am still a rather new pool owner who is getting well experienced with addressing problems with algae, filters. etc. And my experience so far is telling me to get rid of the sand filter. Sounds like cartridge is a WHOLE lot easier to maintain. Who can argue with hosing off a filter once a month(10 minutes?), buying a new filter cart. every, what 2 years? versus backwashing, leaking, repairs and such. I may stay away from Hayward too considering the problems with their product. One question I do have for cartridge owners is what size do I get? I have an AG pool 4 1/2 ft, 27 ft diameter round. Hayward 1 1/2 hp pump, 70GPM. Do you also recommend a certain brand other than hayward?

[gordyjamz]

Ok here's my opinion so far reguarding sand. If you don't minda slight haze to your water, I suppose its ok. I'm looking to buy a cartridge. Why you ask, I'll tell ya. We bought our house last year with this pool already here. after two weeks the filter was leaking from the backwash pipe. Needed a new spider gasket. Only 12 bucks at the pool store. OK So I put a new one in, worked fine for the rest of the season. This year it was fine till a few days ago. Guess what its leaking again. It's a hayward swimpro. The guy who sold me the house said he just replaced the sand the year prior(2004). Everyone says the sand should be good for up to 6 years? Well I don't know what to believe. water's hazy. I must say I think i fell for something, because common sense told me " how can water be filtered from sand?" I am still a rather new pool owner who is getting well experienced with addressing problems with algae, filters. etc. And my experience so far is telling me to get rid of the sand filter. Sounds like cartridge is a WHOLE lot easier to maintain. Who can argue with hosing off a filter once a month(10 minutes?), buying a new filter cart. every, what 2 years? versus backwashing, leaking, repairs and such. I may stay away from Hayward too considering the problems with their product. One question I do have for cartridge owners is what size do I get? I have an AG pool 4 1/2 ft, 27 ft diameter round. Hayward 1 1/2 hp pump, 70GPM. Do you also recommend a certain brand other than hayward?

[huskerfan]

I love my DE filter! Ya it takes an extra 5 minutes to mix the DE powder with the water... but you'll save much more time by not having to backwash as often. I don't believe in "bumping" it either, it's doing it's job, if the guage reads it needs cleaned, clean it.

I'm a little confused - everyone's trying to get DE filtering quality out of your sand and cartrige filters, why not just use a DE filter?? Our local pool stores totally hate and advised against using a DE filter in our state as we have a high iron issue in our water. I can honestly say that that is even more reason to use a DE filter too! There are a few local people struggling to get the iron filtered out of their pools with their sand filters that the local pool store advised them to get, and have rustish brown water while mine is crystal clear. Take care to not inhale DE by all means, but I'd much rather add my DE powder than my muratic acid!

All boils down to personal preference- a crystal clear pool is a crystal clear pool no matter which way it's achieved!

[huskerfan]

By cleaning it - I mean backwashing it. I think it's overkill to tear it down and clean it each time to me.