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Thread: What size pump should I have for my pool?

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    What size pump should I have for my pool?

    Pool size is around 13,500 gallons. I have 5 ports in the pool for curculation. Pentair DE filter system. I think my pump may be undersized. Its a challenger pump.
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    Why do you think it is undersized? For just circulation, you don't need a large pump at all and for filtering, you don't want a large pump. I have a 1/2 HP for a 20k pool.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: What size pump should I have for my pool?

    I am not getting any flow through 3 of the ports. All on the same side of the pool.
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    Absolutely no flow or just reduced flow? It is probably a plumbing issue, not a pump issue.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: What size pump should I have for my pool?

    No flow at all. Had a 1 1/2 hp motor and changed it out to 3/4 hp and haven't had flow since.
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    Did they just change the motor or the entire pump? Are there valves that control the flow to each section of the pool? It could be they were just set incorrectly.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: What size pump should I have for my pool?

    Changed out the entire pump. No valves to control the flow. Just an outlet from the pump through the DE filter back to the pool. One line that I am guessing splits underground to feed both sides of the pool. I really don't know as I am new to this pool stuff.
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    Was any of the plumbing past the filter modified? It just doesn't make sense that there is no flow to the other ports without a blockage. All ports had flow before the change in pump correct? Also, what is the filter pressure?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: What size pump should I have for my pool?

    No changes after the filter and currently the pressure on the DE filter reads 25#
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    25 PSI is very high pressure for a 3/4 HP pump. It sounds like there is a blockage in the line somewhere. Could be the filter but since you are getting flow to 2 of the 5 ports, it is most likely the line that has the 3 dead ports. Not sure how it got blocked though because return side blockage is usually pretty rare.

    If all 5 lines worked fine before the installer changed pumps, then I would get the installer back out to explain what happened. He must of done something to cause the problem.

    What is the model # of the pump?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: What size pump should I have for my pool?

    This is what I can see on the pump. Challenger 3/4 hp 16.7 SF. Looks like the model #35213.

    How would I go about unplugging the ports. Run a pig through them? Not sure what direction the piping is going and the previous owner is of no help. Thought about trying to run it backwards from the farthest port and go from there.
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    Return ports are hard to flush out because you have to block all the other ports and then use a hose to try and flush towards the filter. You might try a snake/pig and see if that helps but it is hard to navigate the 90s. Does the filter have a recirculate mode and does the flow out of the returns change at all? Also, what size is your plumbing? Also, when was the last time you backwashed the filter?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: What size pump should I have for my pool?

    Piping is 1 1/2". Don't have a recirculate mode it either backwashes or runs through it normally. Backwashed maybe 3 weeks ago, but this has been a problem for over a year. (the flow from the other 3 ports that is) Do they usually split the flow to the ports on either side of the pool or is it probably just one line running around the outside and deadheading at whatever would be the last port?
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    Usually it is whatever is more convenient for the installer. Unfortunately, most PBs don't really care much about performance.

    But I just want to clarify something. Did all 5 ports ever work properly since you have owned the pool? Did this problem surface when the pump was changed?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: What size pump should I have for my pool?

    Yes all five ports worked when the old pump a 1 1/2 hp motor was there. I am the one that installed the new motor so as far as anything downstream of the filter, nothing was changed from that point on. Don't know why 2 of them are flowing but the other 3 are not.
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    Could you post a picture of your pad equipment and plumbing?

    http://www.troublefreepool.com/threa...oto-s-Tutorial

    Maybe I can find something from that.

    But to confirm and you didn't say directly: Did this happen immediately after you replaced the pump?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: What size pump should I have for my pool?

    Yes, after I installed the new pump I no longer had flow through the other 3 ports. I will try to post some pics in a few.
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    Sorry one more follow up. Did the old pump fail and you left the pool idle for a while when waiting for the new pump? Just a thought on the high filter pressure being a result of an algae bloom which would reduce the flow rate to all ports.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: What size pump should I have for my pool?

    Here are some pics of my setupPool pump pics 018.jpgPool pump pics 017.jpg

    - - - Updated - - -

    Its the ports on the left side of the pool that are not working and I am not useing the inline puck chlorinator anymore. Liquid bleach only.

    - - - Updated - - -

    The pool has never went more than a day without a pump. Lost flow to the other 3 after the pump change. Went from 1 1/2 HP to 3/4HP. I did alot of research and based on the pipe and pool size and pump curve, I found that I should be able to use the smaller HP to do the job. Now I am wondering if I went to little and the 1 1/2 was the right size.

    - - - Updated - - -

    I am going to clean the filters again tomorrow once I get home from work and see if the pressure drops any.
    13,500 gallon pool without a spa Inground
    Pool built by previous owner in 1995 but replasterd in 2008
    DE filter (pentair FNS plus 48,Challenger 3/4 hp pump,In line chlorinator (switching to liquid bleach)
    Using TF-100 pool testing kit

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    mas985's Avatar
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    Re: What size pump should I have for my pool?

    No you were right, a 3/4 HP is more than enough pump. There is clearly something wrong with the plumbing. Cleaning the filters is a good first step because it is important to get a clean filter pressure reading to help with the troubleshooting. If the pressure still does not drop, then there must be something blocking the return line somewhere and unfortunately probably where the two side split.

    BTW, what was the filter pressure with the old pump?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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