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Thread: Abrupt loss in return pressure

  1. Back To Top    #1

    Join Date
    May 2009
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    Dallas, TX
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    Abrupt loss in return pressure

    Any ideas what might cause this? I didn't actually observe it happening, but Saturday all was normal, then while I was swimming in the pool Sunday I noticed the significant loss in pressure. It happened to coincide with the addition of salt to the water, but I don't see how the two could be connected.

    Thanks,
    Dave
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

  2. Back To Top    #2

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    Re: Abrupt loss in return pressure

    Oh, BTW, I meant to add that filter pressure seems normal. Gauge reads zero when pump not on, then goes up to the normal operating pressure when pump is turned on.
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    Re: Abrupt loss in return pressure

    Blockage in the impeller can cause pressure to drop. if some salt got sucked in an temporarily clogged it that could be your issue.
    Kidney shaped ~ 10000 gallon Ig Plaster pool with pool cage. 120sf Cartridge filter. Pentair WhisperFlo WFDS-26, 230 Volt, 7.8/3.0 Amp, 1-1/2 Horsepower 2 speed pump, Solar panels on the roof. Heliotrope HelioMatic 4000D solar controller.

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    Re: Abrupt loss in return pressure

    Quote Originally Posted by mdhwoods
    Blockage in the impeller can cause pressure to drop. if some salt got sucked in an temporarily clogged it that could be your issue.
    OK, if that's the case then it should resolve itself. However, it is an old pump. Let me ask an ignorant question: What are the signs that the impeller needs to be replaced apart from a blockage?

    Thanks,
    Dave
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

  5. Back To Top    #5

    Join Date
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    Re: Abrupt loss in return pressure

    If the impeller is clogged, it only needs to be cleaned out.

    Very rarely an impeller will snap off it's stem - could be what's happening with your pump, more likely if it's the original impeller on an old motor. Changing out an impeller is as easy as changing a shaft seal (there a a number of posts here on changing the seal) - but that's only because it's the exact same thing Speaking of the seal, if you do need a new impeller, change the seal, they don't like being taken off and put back on!

    There's only 1 thing the gauge reads normal, if it was a bad impeller, you'd need to have some sort of obstruction to jack the pressure up to normal. Are you loosing water? It's starting to sound like a broken return line
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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