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Thread: Moved to Cartridge Filter and new Pump - Opinions and Math Help Needed (Redux)

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    Moved to Cartridge Filter and new Pump - Opinions and Math Help Needed (Redux)

    After getting some help earlier this year, I think I might have messed something up.

    Equipment -:
    Installed a doughboy 18'x34' with ~7' deep end (~21K gallons) last year, replaced sand filter (silica II) with Pentair 420 cartridge filter and 2hp pump (20amp 115v) with a Pentair Optiflo 1hp dual speed pump (1hp/0.12hp). (1) 1.5" return line, (1) 1.5" suction line. Replaced all lines with flex pvc and added a 3 way valve so that I have a waste port when needed. Also have a nifty little Aquabot 4wd rapids that does all the cleaning, there's a jet on top (cleans my walls!) so circulation bonus

    Okay my problem is, that I thought I had a 1.5 hp pump, so i was doing all my math with a 0.75hp low speed in mind. Today everything's open, and I finally got to do the 5 gallon bucket test, and was a little surprised at the results -: ~18 secs for 5 gallons = 1000 gallons per hour, so 20+ hours for one turnover. After going through everything, I realized that the pump was the issue after seeing the label (1hp/0.12hp).

    So my question is this; Do I put this on craig's list (bought it in February, so I missed my return window) and upgrade to a 1.5/0.75 pump or is this enough for me? Keep in mind that I am considering solar panels for the side of the deck.

    Thanks.

    I've attached a picture because it seems kinda nuts that it would cost less than $0.30 a day to run this 24/7 (is running it 24/7 even a good idea?)
    IMG_20140511_153203resize.jpg

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    JasonLion's Avatar
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    Re: Moved to Cartridge Filter and new Pump - Opinions and Math Help Needed (Redux)

    There is no such thing as a 1.5/0.75 pump. For a two speed pump, the HP on low speed is always 1/8 of the HP on high speed, while the water moved on low speed is always 1/2 of the water moved on high speed, and electrical usage is 1/4 per unit time or 1/2 for the same amount of water moved. Also, turnovers are not really important, that is just an old rule of thumb from the commercial pool world that doesn't really apply to residential pools. There is no point in running 24/7, though some people do that. A typical pool only needs four or five hours of run time to keep everything working well (more if something is going wrong), and yes that is still true at 16 GPM.

    In any case, that pump should be just fine for your pool.
    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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    Re: Moved to Cartridge Filter and new Pump - Opinions and Math Help Needed (Redux)

    Thanks JasonLion,
    I obviously got my something mixed up when it was explained to me before. But your explanation leaves me with a question; Might there be something wrong if I'm only getting 16GPM? i'll go do a test at full speed and see what results I get.

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    JasonLion's Avatar
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    Re: Moved to Cartridge Filter and new Pump - Opinions and Math Help Needed (Redux)

    16 GPM is a little lower than I would expect, but not off by enough to think that there is something wrong.
    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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    Re: Moved to Cartridge Filter and new Pump - Opinions and Math Help Needed (Redux)

    It might be because I used a 40 foot vacuum hose, when I do the test I'll cut a small section of flexPVC to minimize friction.

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    Re: Moved to Cartridge Filter and new Pump - Opinions and Math Help Needed (Redux)

    Using a shorter piece of FlexPVC (3ft vs 40 ft of vacuum hose), we tested it again directly attached to the return with a barbed adapter and holding it tight over the eyeball return. For the 5 gallon half speed test, directly attached we averaged (rounded up) 11 seconds, so ~27 GPM, and holding it over the eyeball 12 seconds, so ~25 GPM. At full speed we saw a little less than double the gain, which at the end of the day is a lot better than 16 GPM at half. I've noticed that the included return with the doughboy pool sucks, so I've order one from Hayward so that I get a little more control with the direction. Thanks Jason.

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    JasonLion's Avatar
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    Re: Moved to Cartridge Filter and new Pump - Opinions and Math Help Needed (Redux)

    Great!
    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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