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Thread: Too Big Pump - downsides?

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    Too Big Pump - downsides?

    When we purchased our pool package at the end of the season last year, they only had 2 hp pumps available. Us not really knowing much about pumps, we just went with it (of course, at no point did the pool store tell us that it was way too big for our pool).

    Are there any other downsides to this that I should be aware of other than it will be costing us more in electricity (curious as to how much more we'll be using with such a large pump)?

    TIA!
    21' round 54" AG Wilbar Quest; ~11,000 gal//Hayward Easy-Clear 125 sq ft Cartridge filter//Hayward Power-Flo LX 2hp pump

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    Mod Squad JohnT's Avatar
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    Re: Too Big Pump - downsides?

    Cost is the big one. You can get debris driven through the filter or even damage to the filter in extreme cases with some filters. With the short plumbing runs of an AG pool, it's not as big an issue as with an IG. You might have trouble vacuuming as your pump may starve for water with the hose connected.

    Your pool could easily get by with a 1HP pump or maybe even a smaller one. The larger pump may circulate the water faster, so it may not cost twice as much to run it.
    TFP Moderator
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    Re: Too Big Pump - downsides?

    What size plumbing do you have? 1 1/2" pipe?? Some filters are less efficient with too high of flow (most notably sand and DE). You can also get cavitation which makes it difficult to vaccum and can damage the pump. Do you have any trouble vacuuming? That's usually where cavitation is first seen. I could not run our old 1.5 HP 2 speed pump on high to vacuum as it would cavitate and loose prime.
    18' round, 52" deep Kamika/Nuance by trevi;
    1HP/2 speed Hayward pump/150 sq ft cartridge filter
    Aqua Trol

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    Re: Too Big Pump - downsides?

    We have a cartridge filter if that makes any difference?

    The pool is still closed (hoping to start opening process tomorrow, weather permitting) but when I vacuumed at the end of last season, I didn't have any problems with suction or the pump seeming to need additional water. I will keep an eye on that though.

    ETA: Yes, I'm pretty sure it's 1 1/2" piping.
    21' round 54" AG Wilbar Quest; ~11,000 gal//Hayward Easy-Clear 125 sq ft Cartridge filter//Hayward Power-Flo LX 2hp pump

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    mas985's Avatar
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    Re: Too Big Pump - downsides?

    Quote Originally Posted by KurtG
    What size plumbing do you have? 1 1/2" pipe?? Some filters are less efficient with too high of flow (most notably sand and DE). You can also get cavitation which makes it difficult to vaccum and can damage the pump. Do you have any trouble vacuuming? That's usually where cavitation is first seen. I could not run our old 1.5 HP 2 speed pump on high to vacuum as it would cavitate and loose prime.
    I need to correct something here. You cannot "see" cavitation in a residential pool pump, you can only hear it. Cavitation bubbles can only exist under very extreme suction and once they travel from the inlet to the impeller vanes they collapse so cavitation bubbles can't exist beyond the impeller. And second, cavitation would not cause loss of prime. More than likely what you are experiencing is an air leak and not cavitation. It is actually very hard to cavitate a residential pool pump. Most pumps will suck in air and lose prime well before the pump cavitates. Now here is a pump that you can see and hear cavitation.


    Quote Originally Posted by xtencornfield
    We have a cartridge filter if that makes any difference?
    What size is the cartridge?

    What is the model/brand 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: Too Big Pump - downsides?

    Quote Originally Posted by mas985
    [
    Quote Originally Posted by xtencornfield
    We have a cartridge filter if that makes any difference?
    What size is the cartridge?

    What is the model/brand pump?
    I'm not at home but I'll check later. Both the pump and filter are Hayward, I know that much!
    21' round 54" AG Wilbar Quest; ~11,000 gal//Hayward Easy-Clear 125 sq ft Cartridge filter//Hayward Power-Flo LX 2hp pump

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    Ohm_Boy's Avatar
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    Re: Too Big Pump - downsides?

    Now here is a pump that you can see and hear cavitation.
    I had a little cavitation on this pump some years ago, but we couldn't see it. You sure could hear it though.
    [center:1ak45ecq][/center:1ak45ecq]
    Oh yeah - it's oversize for a pool.
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

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    Re: Too Big Pump - downsides?

    Quote Originally Posted by xtencornfield
    Quote Originally Posted by mas985
    [
    Quote Originally Posted by xtencornfield
    We have a cartridge filter if that makes any difference?
    What size is the cartridge?

    What is the model/brand pump?
    I'm not at home but I'll check later. Both the pump and filter are Hayward, I know that much!
    Didn't have time to get back to this until now (opened our pool in the meantime, whooo!).

    I have a Hayward Power-Flo LX 2hp pump and a Hayward Easy-Clear 125 sq ft cartridge filter
    21' round 54" AG Wilbar Quest; ~11,000 gal//Hayward Easy-Clear 125 sq ft Cartridge filter//Hayward Power-Flo LX 2hp pump

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    mas985's Avatar
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    Re: Too Big Pump - downsides?

    The filter should be able to handle that pump. The real issue is energy use.
    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: Too Big Pump - downsides?

    Quote Originally Posted by mas985
    The filter should be able to handle that pump. The real issue is energy use.
    Ok, thanks. Since I have no idea how much more energy we'll be using, it makes it difficult to decide whether or not it might be beneficial for us to try to get a smaller pump and sell this one...or something.
    21' round 54" AG Wilbar Quest; ~11,000 gal//Hayward Easy-Clear 125 sq ft Cartridge filter//Hayward Power-Flo LX 2hp pump

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