Pump & Filter Selection

[Schnozz]

After many posts, many threads, and too many questions I have decided to go with a cartridge filter set up. I've shifted from sand to cartridge for a couple of reasons. First, water restrictions in So. California are only going to get tighter. Seems to make more sense as I will not have to backwash the filter. Second, it appears I can get more gpm flow with the same size pump if I go with a cartridge filter instead of a sand filter. Contemplating a
Pentair 1-1/2 HP, 2-speed motor with 150 sqft cartridge.
(PNCC01500F2160). Does that seem to be enough overkill for my little Intex or would anyone recommend I jump up to a 200 sqft or even a 240 sqft cartridge? (Looking at the specs, I think they run with the same motor) I'm thinking that even the 150 sqft set up will let me upgrade to a 16 x 32 Intex if I decide to do that in the future. How do my logic and my calculations sound?

 

[duraleigh]

An 8500 gallon pool will do nicely on a 1 hp 2 speed. I would drop back to that size. Get the biggest cartridge filter that fits the budget.

 

[Schnozz]

Thanks for the reply....Obviously, that combination won't come as a set from Pentair. So it would be ok to by a 1 HP 2-spd pump and the largest Cartridge filter I can afford from Pentair as seperate items? (or wherever) That's what I'll look into. Would the 1 HP 2-spd be enough if I added solar (First Floor Patio Roof, up about 9 ft.) or if I upgraded the pool to a 16 x 32 in the near future? I'm also moving the equipment about 30' from the pool at the same elevation.. Solar is between the equipment and the pool, just up 9 ft.

 

[mas985]

You will get a much better deal with the combo units. The PNCC0150OF2160 is a good setup. Don't worry so much about pump size because all of the pumps in the combos are not that big even though the labels would indicate otherwise. AG pumps tend to be much smaller than IG pumps for the same label and the 1 1/2 HP pump is actually about the same size as my 1/2 HP IG pump. Pump labels can be very deceiving.

As for solar, either pump is fine for a single story install.

 

[Schnozz]

Mas.....So, no need to worry about a much larger cartridge filter for my needs? Looking at the specs it did seem to me that the 150 sq-ft filter would be enough overkill for my pool.
And, I just did some math. Your pool is about 2-1/2 times the volume of mine. Your cartridge filter too is about 2-1/2 times bigger, at 420 sq-ft, than the one you recommended for my needs at 150 sq-ft.
I see that my tendency, at first, was to go with a bigger pump, now I'm looking to go with a bigger filter than I need. I'm going to try to keep it simple. Thanks again for continuing to assist.....

 

[mas985]

I think 150 sq-ft is fine for your size pool. I clean my filter once per year and most times the PSI has not even risen so I could have gone with a smaller filter and still clean it once a year.

 

[Schnozz]

I did my final bit of agonizing over the cartridge filter I'll be purchasing this fall from Pentair. The PNCC0150F1160 looks like the setup for me. 1-1/2 HP, 2-Spd motor (150 GPM) and 150 sqft Cartridge Filter. When looking at the spec sheets on the Pentair web site for combination set ups a little closer, I noticed something interesting. All the combination set ups (150 sqft, 175 sqft, and 200 sqft) move 72,000 gallons in 8 hours. (Or 150 GPM), regardless of the pump/motor size (1-1/2 or 2 HP). Then I looked at what Pentair calls the CC Plus Cartridge Filters (Just the filter w/o a pump). The 240 sqft moves 90 GPM and the 320 sqft moves 120 GPM, These models, with larger sqft filters, move less water than the 150 sqft model I selected. The 520 sqft and the 420 sqft moves the same 150 GPM as the 150 sqft model I selected. I am at a loss to understand that. Does anyone know why that is? I think that's the reason making a selection can be so confusing. Is the spec sheet correct?
OK, Rant Over...

 

[mas985]

Usually, they will spec residential filters at 1 GPM/sqft and commercial filters at 0.375 GPM/sqft. So what you are seeing is a different spec, commercial vs residential. The 0.375/sqft is the NSF 50 recommendation and the same metric I use in the filter sizing table in the Hydraulics 101 sticky and more realistic suggested top flow rate (not absolute maximum). Also, they will usually cap the spec at 150 GPM because there is no residential pump that can really deliver that much flow rate anyway. I wouldn't get too concerned about those specs because they really won't apply in your case.

 

[Schnozz]

So, if I understand you. The NSF spec for the set up I'm looking at, the Pentair PNCC0150F1160, is for residential filters and that spec is 1 GPM/sqft. Hence the 150 GPM for the
150 sqft filter. But if it was being presented/sold as a commercial set up, the NSF 50 Recommendation for Commercial Pools would spec that set up out at about 56 GPM. Is 56 GPM the figure I should used when calculating head loss and such or the 150 GPM figure? Also, those are the factors (1 GPM/sqft & .375 GPM/sqft) for Cartridge filters, correct? Sand and DE would have a different GPM/sqft factor?

Still plenty of filter (GPM) for my needs, just seems to be a bit confusing. Nice if there was a little more standardization. I could see how it would be easy for a layman, like me, to be talked into the wrong piece of equipment simply in the way the specs are presented by the salesman. But no worries all pool builders and pool stores are crazy honest, so we're safe.....LOL. Fortunately, we have TFP to guide us....

Thanks for the clarification. From now on, if I see the specs for a particular cartridge filter, I can do a little math and and figure out what they mean...

I'm starting to believe the hype. You are the "pump genius".....

 

[mas985]

The NSF spec for the set up I'm looking at, the Pentair PNCC0150F1160, is for residential filters and that spec is 1 GPM/sqft.

Not quite. NSF/ANSI 50 was originally written for public pools (i.e. commercial) only and they specified 0.375 GPM/sqft. They don't have a specification for residential although some cities have adopted the same for both residential and public. I am not sure where 1 GPM/sqft originally came from but many manufactures use that for residential filters.

But if it was being presented/sold as a commercial set up, the NSF 50 Recommendation for Commercial Pools would spec that set up out at about 56 GPM. Is 56 GPM the figure I should used when calculating head loss and such or the 150 GPM figure?

Why do you need to calculate head loss at all? And no, you wouldn't use 56 GPM because that is probably not the flow rate that your system will actually have. Head loss is very difficult to calculate but it is dependent on not only the entire plumbing system but the pump you use as well. It is almost never necessary (or worth it) to calculate head loss other than for curiosity.

Sand and DE would have a different GPM/sqft factor?

Yes they do. And is 15 GPM/sqft and DE is 2 GPM/sqft.

 

[Schnozz]

I really don't need to calculate head loss. I was just thinking out loud. You, Duraleigh, pooldv and a couple others on the site have assured me the Pentair pump (1 or 1-1/2 HP) I had selected was plenty (GPM) to do what I'm imagining in my future. I was just curious if that's what the calculations were based on. But it's not flow (GPM) of the filter that calculation comes from but the GPM of the pump. The filter would add to head loss calculations.... I should have been able to reason that out..

Clear and concise explanation. You're the man... Thanks again

 

[mas985]

No calculations at all are necessary.

For filtering and circulation, any pump would do because the flow rate requirements for that are so low. For solar, you just need a pump with enough head for the solar lift but again, nearly any pump can do that. About the only pump that is too small for solar is an Intex. Even my 1/2 HP is more than enough for solar on a two story roof.

 

[Schnozz]

Well fortunately for me, and fortunately for us laymen on the forum, we don't have to worry about calculating which pool motor/pump/filter would be best. Or figuring out head loss and such. That information is available to us through the experts on the TFP forum, with no strings attached. And as can be seen in many of the responses to my questions, the answers come from practical wisdom born from years of experience and study. I will never have access to the all information or depth of knowledge available here to do the calculations accurately anyway. The experts on TFP understand the mechanics of water flow and the ins and outs of electric motors. It seems to come to you naturally, buts it's from years of careful research and deep study. For example, on several occasions it's been brought to my attention that 1-1/2 HP may not be actually 1-1/2 HP. And that motor labels can be deceiving.
In fact, in one post mas985 said his 1/2 HP pump is probably the same size as the 1-1/2 HP Pentair pump in the combination set up I'll be buying. With all the options available to me, just choosing any pump seemed a daunting task. But not any more. I may not be able to calculate head loss or explain principles of liquid flow or understand motor dynamics, but from all the responses I've gotten, I can read a pump curve and a spread sheet and make an informed decision. Me, my wife and my 8600 gallons of water thank each and every poster who has responded to my incessant question....and thanks to TFP for keeping up the good work.....
As I upgrade, I will probably have more questions. I look forward to the help of all ya'll.