[NA]sizing pump for pool project[NA]

Let'sgoflying!

Let'sgoflying!

Touchdown! Greaser!
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Dave Taylor
I built a solar collector for the pool: 200' of 1/2" black poly tubing coiled up in a case.
The aquarium pump which worked well with 100' of 5/8" garden hose lying on the sidewalk is not up to the job.
To get an idea of what is required to push water through this device, I tee'd in a gauge to the garden hose and cranked up the water til it was flowing at a rate which looked visible acceptable.
The gauge says about 4psi and at that pressure, we are running about 1gpm.
There is very little rise needed in addition to this; maybe a foot.
The plan is to put the pump in the (30" x 8' dia) pool and pump out to the collector, and a return line drops water back in the pool.

Think the -400 model will work? (I see no psi specs)
Any other suggestions?
http://www.lifegardaquatics.com/products/

I am thinking I will tee in a (manual) relief valve if the pump I get is seeing too much resistance.
 
Have to watch the head spec.... Which is how high the pump will lift the water. Check out taco pumps for hydronic heating systems.
 
Let'sgoflying! said:
Its only lifting the water a foot at most.
Click to expand...

Shouldn't have to do any lifting if the outlet of your loop goes back into the pool. All you'll have to overcome is the friction loss in the tubing. In heating/plumbing, many of the circulation pumps are made by Grundfos. You would probably want a stainless steel or composite volute and impeller if you are pumping pool water.
 
1 GPM? That ain't much. With 8 hours of sun/day, you're only "touching" 500 gallons of water. Is a pool cover out of the question? Yeah, I know they say "solar pool cover", but most of the benefit is from preventing cooling by evaporation.
 
The proper way to do it is construct a system curve - total hydraulic gradient in stepped flow increments and superimpose the pump curve, which you can construct from the flow vs. head data points on the chart.

I just ran a quick calc for 1 gpm @200 feet of 0.5 inch ID pipe - 3.3' of head loss, and that's not accounting for minor losses. So your 400 model ain't gonna work.
 
kyleb said:
1 GPM? That ain't much. With 8 hours of sun/day, you're only "touching" 500 gallons of water. Is a pool cover out of the question? Yeah, I know they say "solar pool cover", but most of the benefit is from preventing cooling by evaporation.
Click to expand...

600gal pool, thinking 1gpm is fine; it did ok with previous system
Using pool cover to keep bugs out but the pool is under a carport.
Think really small pool
 
Sac Arrow said:
The proper way to do it is construct a system curve - total hydraulic gradient in stepped flow increments and superimpose the pump curve, which you can construct from the flow vs. head data points on the chart.
Click to expand...

um. what'd'he say??
 
Let'sgoflying! said:
ok. The one that worked for 2 years was a stupid $9.99 pump from Harbor freight. Thinking I can probably do this for <$50
Click to expand...

Right. But either way you are going to have to go with an oversized pump and run it near dead headed. It's an awkward flow to work with. It's too small for the smallest Grundfos style booster, and too large for a diagram metering pump. At least, an economical one.
 
Let'sgoflying! said:
I built a solar collector for the pool: 200' of 1/2" black poly tubing coiled up in a case.
The aquarium pump which worked well with 100' of 5/8" garden hose lying on the sidewalk is not up to the job.
To get an idea of what is required to push water through this device, I tee'd in a gauge to the garden hose and cranked up the water til it was flowing at a rate which looked visible acceptable.
The gauge says about 4psi and at that pressure, we are running about 1gpm.
There is very little rise needed in addition to this; maybe a foot.
The plan is to put the pump in the (30" x 8' dia) pool and pump out to the collector, and a return line drops water back in the pool.

Think the -400 model will work? (I see no psi specs)
Any other suggestions?
http://www.lifegardaquatics.com/products/

I am thinking I will tee in a (manual) relief valve if the pump I get is seeing too much resistance.
Click to expand...

I'd look at a pentair variable speed, loved mine when I had my house with a pool. New house is waterfront so it self pumps lol
 
no no, that's drinking like a fish. Not saying your beer is safe from me however.
 
Let'sgoflying! said:
I googled a spec on this pump which says something like 'can function in 145psi environment' - pretty sure there's no way this will develop 145psi in any circ's. Maybe they mean in a closed system which has a preload applied.
Click to expand...

It says the maximum head is 9.8 feet, and maximum flow is 2.1 gpm. At 1 gpm head will be somewhat less. It should work or it's close enough.
 
Let'sgoflying! said:
I googled a spec on this pump which says something like 'can function in 145psi environment' - pretty sure there's no way this will develop 145psi in any circ's. Maybe they mean in a closed system which has a preload applied.
Click to expand...
Yes, it would work with high static heads. It’s just a comment on the seals.
 
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