Sand or cartridge filter?

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The NSF maximum for public pools is 15 gpm/sq.ft for sand filters.
So given the pump max of 2500 gph = 42 gpm

The 14" = 1.07 sqft --> 42/1.07 = 39 gpm/sqft
The 16" = 1.4 sqft --> 42/1.4 = 30 gpm/sqft

In reality the 2500 pump is no likely pushing 42 gpm, so the ratio are probably better, but that pump still may be a little large for those filters. That said, many people are using them and happy with the combo.
 
bobodaclown said:
@ Linen: No offense taken.
Click to expand...
:cheers:


Jbliz beat me on this, but I thought I would post my numbers, since they are a little different:

bobodaclown said:
Sounds like the 2500gph with with the sand may be a good compromise. Not sure if the pump flow rate would be too high for the sand filter though.
Click to expand...
The larger intex sand filter is actually 2650 gph, or about 44 gpm and is 16 inches in diameter = ~ 1.39 sq.ft. The NSF maximum flow rate for public pool sand filters is 15 gpm/sq.ft. That gives us 44/1.39= 31 gpm/sq.ft, so this filter too does not meet the NSF requirements...but it is much closer at 210% for the 2650gph sand filter verses the 750% of the 2500gph cart filter. The op currently has the 1600gph sand filter (actually they mentioned 1500gph sand filter, but intex does not list that size) that is 14" in diameter which equates to ~ 1.1sq.ft. 1600 gph equals ~27 gpm, so 27/1.1= 24.5 gpm/sq.ft...so a little better at 163% of the NSF public pool requirements.

To summarize for easy reading and adding other intex filters for completeness:

  • Intex 1600gpm 14" sand filter: 24.5 gpm/sq.ft. (163% of nsf)
    Intex 2650gpm 16" sand filter: 31 gpm/sq.ft. (210% of nsf)


    Intex 530gpm A type cartridge filter: 1.77 gpm/sq.ft. (472% of nsf)
    Intex 1000gpm A type cartridge filter: 3.33 gpm/sq.ft. (889% of nsf)
    Intex 1500gpm B type cartridge filter: 1.67 gpm/sq.ft. (445% of nsf)
    Intex 2500gpm B type cartridge filter: 2.78 gpm/sq.ft. (741% of nsf)

One other note on the sand filters, Hayward uses a specification of 20 gpm/sq.ft. max for their residential sand filters, and pentair appears to use 25 gpm/sq.ft. max on their smaller filters. So that bring the intex sand filters very close to the major manufacturers sand filter specs.

As jbliz mentioned, these pumps are not moving their specified gph (especially with the corrugated pipe that intex supplies with their equipment) so the sand filters likely start approaching the 15 gpm/sq.ft. requirement. However, the cartridge filters never get close. Unfortunately, intex does not publish performance curves afaik, so without empirical data on flow rates we can only go by the spec.
 
Once I made the decision to go with the Intex line of sand filters, I had to decide between the 1600 GPH (I believe what you have) and the 2650 GPH. I went with the 2650 to make sure I had plenty of suction to run my vacuum and I figured the additional filter capacity would be better for less frequent back washes. The vacuum works great and I went over two months without need to backwash. Next year I'll see how long I go without a back wash since I'll be starting with it at the beginning of the season.

If you have plenty of suction to run your vacuum and you're not needing to backwash excessively you're probably good to go. If you want a bigger tank or more flow the 2650 addresses that.

I am running the stock Intex plunger valves, hose, and Intex floating skimmer (on a PVC stand to keep in place).
 
Vicsin, let me readdress your original post with a question......are you thinking swimming pools will be part of your life for awhile?

I ask this as the problem with ANY Intex pump attached to any filter type is only a one shot device. What I mean here is that in particular, the electric motor for the pump IS the problem. Having examined my failed 2650 pump/cartridge setup from earlier this year I can tell you that it is not made to be repaired. Can it? I believe so, but with great effort compared to the "major" manufacturers pump setups. The Intex electrical motor is a very heavy, open frame motor, but the problem is that the bearings are not what most of us would consider good bearings.

May I recommend if you are serious about this AGP thing, and in particular, if you plan on getting a larger pool this next season, look at the setups from one of the major manufactures that have a separate (or rebuildable) pump. Your choice of sand, DE or cartridges......that will in my opinion, save you money AND save you frustration over the years.

Bob E.
 
The pump is separate on my new Intex Sand filter. Actually the pump is in my shed right now while the filter is still setting out side on the pad.

Nothing wrong with other options though if you prefer to go another route.
 
linen said:
vicsin said:
Not really, except wanted a more powerful pump to maybe run a vaccum.
Click to expand...
Well that 2500 cart filter will probably have more suction than the 1600 sand filter, but it might also allow some of it back into the pool. Give it a shot (unless you can return it).
Click to expand...

Yes, the 2500 pump does quite well with the vacuum I have. However, as noted above with the numbers posted, the pump IS overdriving the filter by quite a large margin. By those numbers, even at 45 sq ft (if I ever find a third canister) that would still not be low enough flow for proper filtration. I am shooting for .9 gph/sq ft. going by the pump's supposed output. More than likely it is only able to output 2/3 of that at best.

I suspect that the test rig Intex's manufacturers use is an open tank>pump>flow meter>open ended pipe, with all pipe being smooth interior, and no bends. To me that would be the only way they could come up with those numbers.

Until I added the second parallel filter, I was still getting a lot of "blow through" of the fine silt. With two filters in parallel, I am seeing a marked decrease in that, especially when the filters are about halfway to needing cleaning. Suction does suffer at that point.
 
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