Size of Filter & Pump for Upgrade

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dschwarze
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Size of Filter & Pump for Upgrade

Postby dschwarze » Sat 03 Jan, 2009 18:32

Does anyone know what size sand filter tank, pump, and heater would be most appropriate? My pool is 45,000 gal with an attached spa. It is plumbed in 1 1/2 inch pipe. There are 3 returns, 2 on the pool and one for the spa. There are two skimmers, one for the pool and one for the spa. There are 2 main drains also , one for the pool and one for the spa. The current heated is a 275,000 btu Teledyne.

thanks
Dan


SCHARRON
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Postby SCHARRON » Thu 08 Jan, 2009 20:19

THE FILTER SIZE REALLY DEPENDS ON HOW OFTEN YOU WANT TO BACKWASH..MOST TIMES A 24" FILTER WILL DO,BUT BIGGER IS USUALLY BETTER.PUMP SIZE MIGHT BE IN THE 2HP RANGE.HEATER...THE BIGGER-THE FASTER IT WOULD GET THE WATER TEMP UP. GO AS BIG AS YOU CAN AFFORD ON IT. 400K SIZE MIGHT BE NICE
dschwarze
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Re: Size of Filter & Pump for Upgrade

Postby dschwarze » Tue 24 Feb, 2009 15:28

Thanks. I was worried thar a 2 HP pump might be too much pushing through 1.5inch piping (at least one local pool guy told me).

Dan
PoolsUnlimited

Re: Size of Filter & Pump for Upgrade

Postby PoolsUnlimited » Wed 25 Feb, 2009 08:25

Our company usually works on a pool volume turnover rate of 5 hours, which would mean a pump with a capacity of 9,000 gallons/hour!
A 3Hp pump gets close to this figure, though your 1 1/2" pipe would only comfortably sustain a 1.5Hp pump. If the return lines are very short (<10 feet) or they split close to the filter you could probably get away with the 2Hp.
dschwarze
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Re: Size of Filter & Pump for Upgrade

Postby dschwarze » Wed 25 Feb, 2009 21:58

Thank you for your thoughts. My returns split close to the pump; one to the spa and one to the pool. The pool return splits again into shallow and deep end return . All lines are 1.5 inch, the are probably 15' to the shallow; 20' to the spa and 35'-40' to the deep end return. The system originally had a 1 hp pump.

Thanks again
Dan
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Larry
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My Pool: Inground concrete 72m2
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Re: Size of Filter & Pump for Upgrade

Postby Larry » Thu 26 Feb, 2009 03:30

Hi Dan
Here are some things to consider:

  1. Assuming your skimmers each typically provide 25gpm flow (or 1,500gph), then 2 skimmers will give 3,000gph. Opening the pool's main drain will give an additional 2,200gph (max for 1.5" pipe). So we have 5,200gph available for the pump.
  2. We now have a maximum flow rate of 85gpm based on the suction line. Assuming the filter can cope with it, you should choose a pump that can provide this flow rate.This would be a 1.5Hp (or 2Hp) pump, depending on make and model.
  3. A pump providing 85gpm will give a turnover rate of almost 9 hours. The backpressure from the filter and heater may reduce the flow rate and increase the turnover time, but you are limited by the existing plumbing.
Use this as a starting point when you begin shopping around for the pump and filter.
Me...

Re: Size of Filter & Pump for Upgrade

Postby Me... » Thu 26 Feb, 2009 07:55

Egads! To remain in good practice, 1.5" plumbing is pretty much limited to around 45gpm on the suction and 60 on a pressure side. Multiple suction lines run directly into the pump room will allow more flow on the suction side and the same would pertain to multiple outlet lines.

That said, one of the biggest concerns is entrapment and that comes from drawing water too fast out of a main drain or suction fitting. You also have to imagine the situation where you could be drawing ALL the water out of a single drain. So I agree with your original guy on that point at least, a 2hp pump is too big.

All that aside, if I had to do this originally I would use a 36" sand filter and maybe a 1.5hp, 2-speed pump. Hi speed, somewhere around 120gpm, for chemical additions, backwashing, vacuuming or parties etc. Lo speed, maybe 60gpm for the spa cycle and general everyday use. I would even go bigger but you hit the realm of commercial equipment and I do not want to see max flow rates in a filter. Double up on properly sized main drains for safety, its a very minuscule cost increase anyways. I would want to see 6 maybe even 8 floor inlets for good water dispersal. The spa would want 2,3 or 4 inlets depending on if you wanted them to be like jets or not. Assuming you have at least a 20x40 pool 2 skimmers anyways and of course 1 for the spa. And depending on use, times of year to be used, wind and other factors I would bet I would be looking to see closer to a 400k heater there.
dschwarze
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Re: Size of Filter & Pump for Upgrade

Postby dschwarze » Thu 26 Feb, 2009 12:42

The in ground pool was here when I bought the house and has worked ok for the 10 years I have been the owner. Original equipment is a 1 hp Sta Rite pump, Pac Fab 20-22" diameter stainless sand filter, and a Laars 275K gas heater. The pool and the spa run off the same filter. Spa boosters separate independent circuit. Suction side has pool skimmer X 1 and main drain X 1; and the spa has 1 skimmer and 1 main drain. All plumbed in 1.5 inch; through separate gate valves and the 4 into 1 connection then pump. the return divides after the heater int 1 spa return and 2 pool returns; all 1.5 inch and longest run about 40 feet. Since everything needs to be replaced, I was thinking a Sta Rite 1.5 hp, 30 inch Hayward sand, and a 400k Laars. I would try to increase to 2 inch pvc within this circuit.

Thoughts
Thanks
Dan

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