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Thread: Sand filter backwashing procedures?

  1. Back To Top    #1

    Join Date
    Apr 2011
    Far North TX

    Sand filter backwashing procedures?

    Hello noob here again..

    I'm thinking that I need to backwash my sand filter. For how long should I run it in the backwash and rinse positions? I can see little things swirling in the sight glass..does it have to be 100% clear before switching to rinse or how exactly should I do this?

    My pressure is currently about 25 when in filter mode, and when I ran it in backwash mode it was about 10 if that means anything.

    I'm getting a lot of bubbles in the pump basket, and I've checked/lubed/reseated the o-ring several times. If I try to use the zodiac barracuda vacuum it makes bubbles like crazy even though I can see no leaking of air at the vac end, I've checked all the hoses, filled it with water first before starting. If I adjust the jandy valve I can reduce it some, but then the vacuuming is not very effective. Could this be a problem with the zodiac itself? It seems to be cycling/ker-chunking and shaking then it starts moving around and then the bubbles come.

    Any ideas?
    Vinyl liner pool, approx. 10,000 gallon. 1HP Hayward Pump, Hayward Sand filter, Zodiac vacuum, TFP WIP

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Sand filter backwashing procedures?

    When backwashing, the water will usually start clear, then go cloudy, and then eventually turn clear again. Go another 20 or 30 seconds after it gets mostly clear and then stop. Then run on rinse for 30 seconds, then go back to filtering.

    Pressure readings are different on every pool, so we can't tell you if 25 psi is normal for you or not. Lower pressure on backwash is normal and doesn't mean anything.

    That sounds like an air leak in the underground pipe running to the Zodiac, though I am guessing a bit.
    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

  3. Back To Top    #3

    Join Date
    Mar 2009
    Charlotte, NC

    Re: Sand filter backwashing procedures?

    Quote Originally Posted by minmex
    I'm thinking that I need to backwash my sand filter.
    You backwash once the pressure gets to a certain level above what is "Normal Starting" pressure; probably about 9-10 psi above normal but others can be more specific; I think it is a certain pecent increase

    My pressure is currently about 25 when in filter mode, and when I ran it in backwash mode it was about 10 if that means anything.
    I assume you mean it was 10 in the filter mode AFTER you backwashed, right? If yes, that is your "Normal Starting" pressure so when it gets to 19 or 20 you backwash (unless the pros here say otherwise)
    If you meant the pressure was 10 WHILE you were backwashing- ignore that, the pressure DURING backwashing is irrelevant if there even is any pressure reading- I've never looked

    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

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