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Thread: GPM flo by size of pump or motor

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    GPM flo by size of pump or motor

    my hayward sand filter E100 rated 47GPM, my pump is 1.5hp hayward power-flo has 75GPM on motor lable. this is my sand in bottom of pool problem I think. if I go down to 1hp motor can I use same pump or is the GPM the pump or moror size. the pump its self has no GPM on label. thanks , this is my first sand filter. I think they shipped me the motor for the larger filter. pool was installed in june,09 so only 1mth old. bought pool from going out of business sale, so can;t take it back.
    24'x52" AG installed pool June,2009 sand filter Hayward E100 1.5hp pump 13,500gal. auto chlorine feeder

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    spishex's Avatar
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    Re: GPM flo by size of pump or motor

    You can downsize the motor if you also downsize the impeller. If you change the motor but leave the impeller the same, it will still move as much water as it does now, but it will wear out the new less powerful motor.

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    pool4me's Avatar
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    Re: GPM flo by size of pump or motor

    I thought prretty much most applications were like that (Pump higher GPM than filter). Maybe I'm wrong??

    My Hayward pump is 75GPM and my S-T166 Filter is rated at 35GPM.

    I do also get just a touch of fine "sand mist" when the filter first starts (just before I'm about ready for a backwash),

    however . . . I thought that (in my case) that it's attributed to the fact that I have a small layer of Pea Gravel at the bottom of my filter which really "shouldn't be there in a 100lb filter, and (mostly) the fact that my sand level (which should be about 1/2 way up the tank) is about 3/4's of the way up.

    In years past, I think a lot of people used Pea Gravel at the bottom few inches of the filters around the laterals but I don't think it does much (possibly hurts??) in a smaller filter like a 100lb like I have. I'm really happy with the filtering and clarity but I've checked the laterals for breaks (all fine) and still get just a fine mist of sand on start up.

    But . . . even though I backwashed (lots) and rinsed, I do have new filter sand so maybe after a few extended backwashes etc, some of the finer particles will come out. It is way better now then when I first started up.
    I'm going to remove some sand when I winterize this year.

    I'm going to follow this thread to see the coments
    33'x15' x 52" Aqualeader
    Gallons ? - (I use appx 13,500 to calculate "stuff")
    33 x 15 x 4.3 x 5.9 = 12,558. or . . The Pool Calculator = 14,400
    Hayward S-166T 100Lb Sand Filter - Hayward Power-Flo LX 1HP Pump
    Intex S.W.G.

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    JasonLion's Avatar
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    Re: GPM flo by size of pump or motor

    Builders often install a pump that moves more water than the filter is designed for. But that doesn't make it a good idea. Nothing drastic will go wrong, but the filter won't filter nearly as well as it would with a smaller pump and with a sand filter you have a high chance of getting channels through the sand that let dirt go straight throw the filter.

    You almost always want a smaller pump and a larger filter. The smaller pump will save you electricity and the larger filter will filter better and allow you to go longer between backwashing/cleaning the filter.

    Having pea gravel at the bottom of a sand filter is just fine as long as there isn't too much of it. The pea gravel will improve the water flow around the laterals. It isn't normally done that way because it is more work and doesn't make much of a difference on a smaller filter.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    pool4me's Avatar
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    Re: GPM flo by size of pump or motor

    Great comment Jason,

    I was thinking the same thing. I wasn't sure the pea gravel would actually "hurt" and do understand that the idea behind it is better flow around the laterals but I just didn't think (as you mention) that it would cause any noticable difference in a small filter like mine.

    I really should have removed it when I added new sand but instead I just rinsed it and put it back in there after removing the old sand, checking / cleaning the laterals etc.

    In an 100lb filter, the pea gravel doe seem to take away quiite a bit of room in the tank for the actual sand.

    Just for clarification, what would be a "closer / more suitable filter" / pump combo.

    I was thinking either a 3/4 HP pump with this filter or my preferred Idea would be a larger filter with higher GPM rating closer to my pump GPM rating.

    Any thoughts? I bought my current pool from a good friend who bought it about 2 years back, had it installed and the kids preferred their friends in-ground pool next door so they never used it. Got a great deal but always wondered a bit about the pump / filter combo that they used.

    Was considering going with either a larger sand filter or DE Filter as an upgrade. Although this sand filter seems to be doing really well. May sand has "cut down" a really good amount especially after a good vacuum with a nylon stocking over my skimmer basket.
    33'x15' x 52" Aqualeader
    Gallons ? - (I use appx 13,500 to calculate "stuff")
    33 x 15 x 4.3 x 5.9 = 12,558. or . . The Pool Calculator = 14,400
    Hayward S-166T 100Lb Sand Filter - Hayward Power-Flo LX 1HP Pump
    Intex S.W.G.

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