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Thread: Filter lost pressure

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    Filter lost pressure

    My filter pressure was 20psi this morning and I turned the pump off for about an hour then back on. Ten hours after turning the pump back on i'm still only reading 13psi which is what it reads after backwashing. I was wondering why the pressure isn't coming back up to the same level as it was before.
    18x36 ig vinyl
    Pentair Superflo 340037
    Pentair Tagelus TA 50
    Polaris 280 cleaner with pb4-60 booster pump

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    linen's Avatar
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    Re: Filter lost pressure

    Welcome to tfp, RangerXXX

    Does you gauge go to zero when the pump i off?

    When running is there air in your pump basket?
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Filter lost pressure

    It does go to 0 when the pump is off. There is no air in the basket now, but there was a little bubble when it was at 20psi before I turned the pump off.
    18x36 ig vinyl
    Pentair Superflo 340037
    Pentair Tagelus TA 50
    Polaris 280 cleaner with pb4-60 booster pump

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    linen's Avatar
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    Re: Filter lost pressure

    How is the flow at the return?

    If it is low, the first place to look is for a blockage on the suction side of the pool, including partially closed valves, full skimmer, full leaf basket, or some other material plugging the pipes between the pool and the pump, or pump to filter.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Filter lost pressure

    The return is strong like I just backwashed.
    18x36 ig vinyl
    Pentair Superflo 340037
    Pentair Tagelus TA 50
    Polaris 280 cleaner with pb4-60 booster pump

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    Vette's Avatar
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    Jul 2012
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    Ohio
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    404

    Re: Filter lost pressure

    Is there any possibility that you might have a little channeling in your sand?
    11,700 gallon 21' round 54" deep all-resin AGP - June 2012
    Waterway 1HP 2-speed pump / 100 sq ft cartridge filter
    Hayward 150,000btu Natural Gas heater
    I use and recommend the TF-100 for testing

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    Re: Filter lost pressure

    I don't think I have any channeling.
    18x36 ig vinyl
    Pentair Superflo 340037
    Pentair Tagelus TA 50
    Polaris 280 cleaner with pb4-60 booster pump

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    duraleigh's Avatar
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    Apr 2007
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    Sebring, Florida
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    Re: Filter lost pressure

    Your experience is not completely unusual. When the pump is shut off in a tight system, there is a momentary bit of a "slam" in the filter as the pressure drops to zero. It's harmless and nothing to worry about but that can dislodge or disturb a bit of the debris in the filter and loosen it up enough so that water flows through more readily. Like you say, almost as if you backwashed.

    I would backwash anyway and see if you don't get out quite a bit of debris.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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