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Thread: Pressure dropping while shocking???

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    Pressure dropping while shocking???

    I'm in the process of shocking which I have done before. I installed a new gauge this year. It has been showing about 10 PSI but the pressure is going down. When I backwash it returns to 10 PSI. Today when I went to backwash it was 5 and returned to 10??? There are no air bubbles or leaks that I see. The system including the Hayward sand filter are going into their fourth season.

    I must be going crazy from the shocking and brushing. Could it be a bad gauge?
    18' x 36' saltwater inground vinyl pool

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    Mod Squad JohnT's Avatar
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    Re: Pressure dropping while shocking???

    What does your pump strainer basket look like? Does the pressure return to normal if you just turn the pump off for a few minutes and turn it back on?
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
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    Re: Pressure dropping while shocking???

    You have a restriction (maybe a clog) somewhere between the skimmer and the pump. Find that and everything will return to normal.

    The gauge could be bad but not likely from your description.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Mod Squad jblizzle's Avatar
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    Re: Pressure dropping while shocking???

    My thought was a suction blockage as well, but then I could not think why backwashing would return to a higher pressure
    Jason, TFP Moderator
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    Re: Pressure dropping while shocking???

    I will check those things. What's strange is it's going down slowly. It took it 2 days to go from 10 to 5. I backwashed 4 hours ago and it's still at 10. I'll check the system out and report back this evening.
    18' x 36' saltwater inground vinyl pool

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    Re: Pressure dropping while shocking???

    Are your skimmers clear of debris?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pressure dropping while shocking???

    Yes. And both skimmers are pulling water like they always have been. I can't tell about the main drain. The filter basket was not bad either. It's still at 10-11 right now. I guess I'll just see what happens this go round.
    18' x 36' saltwater inground vinyl pool

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    Re: Pressure dropping while shocking???

    If your flow is normal then the thing that is abnormal is your gauge. I have never heard of one doing as you describe but if there is nothing wrong with your flow, it has to be the gauge.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pressure dropping while shocking???

    It did it again. 10 psi dropped to 5. Then back to 10 after backwash. The pressure drops to 0 as it should when the pump is off. Guess ill replace it.
    18' x 36' saltwater inground vinyl pool

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