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Thread: Sudden drop in filter pressure?

  1. Back To Top    #1

    Join Date
    Apr 2013
    Yorktown, VA

    Sudden drop in filter pressure?

    I have a Hayward sand filter that typically operates in my system at about 17 psi. This has suddenly dropped to about 12 psi. The filter is 12 years old. The motor speed seems normal and the return flow to the pool feels normal, so Iím wondering if there could be a problem in the filter where flow is short-circuiting the sand bed, which would drop the pressure while not decreasing flow. (Broken tubes, bad valve gasket?) I figure if there was a problem with the pump not developing the normal pressure (motor running slower than normal, obstruction in the impeller, or a broken impeller), this would be apparent with lower flow than normal at the returns. I replaced the original motor with a 2-speed motor last spring. Although the speed sounds normal, it makes some additional cyclic noise, and has been occasionally since I installed it, but this doesnít seem to affect the motor speed. Any thoughts on what my problem might be? Iíd like to have an informed opinion before I start tearing into stuff to diagnose it. Iím going to buy a new pressure gage today to rule out a bad gage, but I donít know that is a normal failure mode for a pressure gage.
    33,000 gallon, IG vinyl, Hayward Super Pump, 1.5 Hp single speed, sand filter, salt system, built 2002

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Sudden drop in filter pressure?

    The gauge would be my first step.

    If the pressure went from 17 to 12 between closing and opening, then I'd suspect a filter problem. But if it was 17 for a few weeks and all the sudden dropped to 12 with nothing being done to the filter or plumbing, it almost can't be a problem internally.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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