Thread: Pump size for small IG

1. Pump size for small IG

My neighbor just bought a small IG pool he wants me to help plumb it up,

It's only 8x18 it says it's 2200 gal.

He also is going to add the Fafco solar panels I think he's getting 4 4x12's.

We are both just puzzled trying to figure a pump size, the run from the pump to pool is 25', since it's small I think 1 1/2" PVC will be fine.

And the solar will be on a roof just above the pump location, I believe he needs 4gpm for each so 16 gpm for the panels.

since the panels need to circulate thru the pool during the day I think a run time of 6 hours should work.

Now if that is figured to move the water twice a day 2200 x 2 = 4400 that is only 750 gph of water or 12 gpm.

So the pool and the solar need a pump 28 gpm with enough head to pump water to panels.

Did a figure this correctly?

If so what pump can do it?

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2. Re: Pump size for small IG

Did you mean to say it is an above ground pool?

Most solar panels want ~1gpm / 10 sqft. The should be plumbed in parallel so the 4 panels would want a total of about 20 gpm (Fafco's might be slightly less).

Calculating the head loss is difficult and would be required to determine the actual flow rate. Also not sure why you are thinking of turning the water twice per day.

Likely you can get by easily with a 3/4HP pump, but I am still not clear if the pump is below the water level (AG pool) or above the water level (IG pool).

3. Re: Pump size for small IG

this is going to be an in ground pool.

turning the pool 2x a day I thought was the norm, but on such a small pool are you saying it should be more or less?

I was think maybe a pump smaller than 3/4, almost a big pond pump or an aquarium pump.

4. Re: Pump size for small IG

Ok. I just could not picture an IG pool that small. Since the pump will be above the water level, you will need an IG pump with the ability to prime itself.

The first pump that jumps out at me is the Superflo 3/4HP 2-speed pump which should be more than enough for circulation in that pool. I would recommend going with 2" plumbing to reduce head loss (minor cost difference I would think) so that it will have no issue with the solar. Likely will want to have a solar bypass so that not all the flow is sent through the panels.

What is the drain/skimmer and returns setup?
What filter is going to be used? May have to worry about the filter having adequate flow capability.

EDIT: The turn-over is irrelevant. You just need enough to keep the water clear enough of dirt to your liking.

Those small pumps may not be designed for sit above the water level AND be able to pump the water up through a roof, but honestly I am not sure what is out there. This is kind of an odd setup.

5. Re: Pump size for small IG

Originally Posted by jblizzle
Ok. I just could not picture an IG pool that small. Since the pump will be above the water level, you will need an IG pump with the ability to prime itself.
Yes he's putting it in side his lanai and that was the max size, kinda like an Endless pool.

The first pump that jumps out at me is the Superflo 3/4HP 2-speed pump which should be more than enough for circulation in that pool. I would recommend going with 2" plumbing to reduce head loss (minor cost difference I would think) so that it will have no issue with the solar. Likely will want to have a solar bypass so that not all the flow is sent through the panels.
He's going to copy my solar plumbing which has the bypass but he wants the 1.5" instead of 2", I know I agree with you on that, but it's his baby.

What is the drain/skimmer and returns setup?
What filter is going to be used? May have to worry about the filter having adequate flow capability.
He found a cartridge filter that looks good and big enough, it will have one skimmer (maybe one other drain near the bottom) and two returns, I also told him to add a clean out.

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This is kind of an odd setup.
For sure, that's why I'm asking here for ideas.

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6. Re: Pump size for small IG

See my edits above, that may have happened while you were responding.

7. Re: Pump size for small IG

If he is going to depend on using solar heat, then he will need to run the pump when there is sunlight available. Also don't forget you will want to set up a manual bypass valve so part / most of the water flow bypasses the solar panels so you don't exceed their max flow limits / pressure. My gut feeling is any 3/4 HP will be overkill. I am in the process of upgrading / replacing my solar panels, and am using 11- 4x12 Techno-Solis panels, with a target flow of 4.9 GPM per panel, I am using Jandy 2 speed 1.5 HP pump, and all the math says I will still have to allow about 30-40% of the water to bypass the panels when the pump is on hi. One big factor though is the head pressure curve of the pump you have under consideration, my old pump was a single speed 1.5 HP Hayward Super Pump (replaced due to crack in the housing) which is a relatively low head pump and the new pump is a medium head 2 speed 1.5HP Jandy Flo-Pro, at 0 feet of head the Hayward would slightly out flow the Jandy based on published data, however the Hayward has a max head of 50 ft and the Jandy has a max head of 80 ft, at 40 ft of head the Jandy will also flow nearly double the volume of the Hayward Super Pump.

8. Re: Pump size for small IG

Based on discussions with Mark, the 3/4HP Superflo is a pretty small pump and I think a significant jump up to the 1HP that I have.

But I do agree, that for how small the pool and solar setup is, the flow requirements are pretty low ... might even be able to run the solar on low speed if the head loss was kept low enough. Or find a very small pump. Just not sure what is available that is self-priming.

Have to remember, the head loss is not dependant on the pool size it is dependant on the plumbing. Even though the pool is small, the 25' plumbing run with 1.5" is likely more headloss than a typical AG setup and then adding the vertical rise to prime the solar panels.

9. Re: Pump size for small IG

Off the subject, but an 8 x18 pool with 2200 gallons would only be 2 feet deep.

10. Re: Pump size for small IG

Originally Posted by duraleigh
Off the subject, but an 8 x18 pool with 2200 gallons would only be 2 feet deep.
If it was oval it could be 2.5' deep ... this sounds like a small pond to me.

11. Re: Pump size for small IG

That sounds like a "Cocktail" pool. They are very popular in Florida. We vacation on the emerald coast quite a bit and a friend of ours has a home there. It is the first time I saw a gunite pool that looked like a large bathtub. Their pool was only 10x12 feet.

At 8x18 feet it must be more than 2200 gallons. You may want to recalculate the volume. Unless it is only a foot deep that is.

12. Re: Pump size for small IG

it is 54" deep for about 12 of the 18' then steps for the remaining 6 the specs say 2200?

for gallons
L x W x H (All dimensions in inches) = _X_ divided by 231

Looks more like 3500 G

13. Re: Pump size for small IG

I get about 3100 gallons using poolcalculator assuming oval, 4 ft fill depth, and half of the step end being water.

14. Re: Pump size for small IG

it can't be 2200, so if we split our numbers say 3300,

What pump for that size

15. Re: Pump size for small IG

Originally Posted by Nova13
it can't be 2200, so if we split our numbers say 3300

Like jbliz said, the pump is sized more to the plumbing and in this case the solar. How high above the pump is the solar going to be?

16. Re: Pump size for small IG

The bottom of the panels will be 8.5' above the pump, top of panels will be about 14'.

I think the fafco panels use 2" headers, I was thinking that if he uses the 1.5" on the pool as wants to the pipes going up to the panels should be 2".

I double checked fafco's flow rates they look for 4gpm per panel.

17. Re: Pump size for small IG

1.5 v 2"

Cross Sectional Area (in square inches)
1.5 = 1.767
2.0 = 3.142

Maximum Gravitational Vertical Flow - The flow under the power of gravity reaches a maximum in the same way an object reaches Terminal Velocity as it falls through the air. The gravitational force is countered by the waters viscosity (resistance to flow) and the frictional resistance of the pipe.
------gpm---gph
1.5 = 22.5 = 1350
2.0 = 40.0 = 2400

So here on the solar piping the 2" is clearly the way to go I think.

Gravitational Horizontal Flow This is for horizontal applications that do not rely on a pump.
-------gpm
1.5 = 14.07
2.0 = 25.0

http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

and thru fittings, look at 90 v 45 also T's % of loss

http://flexpvc.com/FrictionLossThroughPVCFittings.shtml

18. Re: Pump size for small IG

Another candidate for the pump is a Pentair Dynamo. They make a 3/4 hp 2-speed and it'll prime at about 5 feet above the water level.

19. Re: Pump size for small IG

Ok,I spent some time on the phone with a really good pump company going over this system, he's going to get back to me with his recommendation.

From the way he's talking it's going to be a lot smaller than we all thought and draw very little elec.

He's also getting me a pump for my solar panels on my spa.

let U know

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