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Thread: Sand in the backwash water & bottom of the pool

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    Bob_Funk's Avatar
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    Sand in the backwash water & bottom of the pool

    new pool owner here,

    I have a sta-rite sand filter, older unit & a green pool curently trying to clear the algae, my question is,

    should the sand be flowing out when I backwash?

    I also know there is sand in the pool, when I brush in the shallow end I can see sand floating up with the algae & in the deep end I can feel the pile of sand with the brush but I can not see the bottom yet.

    Where should I start looking?

    Thanks
    I consider myself very lucky I found this site before the pool store found me-pool owner since Nov 2008- Stunningly clear 17,000 gal fiberglass pool, thanks to this site, installed in 1982-24" 3.1sq. ft sta-rite sand filter, 1 hp - 2 speed wisperflo pump-WFDS-4

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    frustratedpoolmom's Avatar
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    Re: Sand in the backwash water & bottom of the pool

    The filter. This is what I found on a similar post:

    Quote Originally Posted by JasonLion
    There are a number of things that might be wrong with the filter. Sand getting through almost always means a cracked or broken lateral pipe. Though there are other things that can break and have the same effect, it is usually the laterals that break first. If you are feeling handy you might want to open it up take the sand out and closely examine all of the laterals and look around for any other problems.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
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    JasonLion's Avatar
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    Re: Sand in the backwash water & bottom of the pool

    Welcome to TFP!
    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

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    In the Industry

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    Re: Sand in the backwash water & bottom of the pool

    Cracked lateral is most likely - however would pay to check the spider gasket inside the valve first as this is usually easier than emptying the filter

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    Bob_Funk's Avatar
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    Re: Sand in the backwash water & bottom of the pool

    Thanks for the replies, I know that the spider gasket is questionable, I had water going out the waste when filtering so I opened it up and reseated it, but next time I backwashed it did it again

    I just put 4 bags of vitroclean filter glass in the filter & I looked at the laterals, but this being my first opool I may have missed something in the filter

    I will replace the spider gasket first as I do not want to take out all the sand
    I consider myself very lucky I found this site before the pool store found me-pool owner since Nov 2008- Stunningly clear 17,000 gal fiberglass pool, thanks to this site, installed in 1982-24" 3.1sq. ft sta-rite sand filter, 1 hp - 2 speed wisperflo pump-WFDS-4

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    spishex's Avatar
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    Re: Sand in the backwash water & bottom of the pool

    It is not uncommon for sand to leave the filter when backwashing since there is nothing but the weight of the sand itself holding it back. This is particularly common after sand changes since the sand might be slightly higher than necessary. If the sand is sneaking past the spider gasket and into the pool during backwash then the new gasket will solve your problem.

    If you have sand entering your sightglass when the filter is on RINSE (which is the equivalent of filter to waste) then you should suspect the lateral assembly.

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    Bob_Funk's Avatar
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    Re: Sand in the backwash water & bottom of the pool

    Thanks,

    I can see the bottom of the pool in the shallow end finally, the pump keeps getting plugged with pine needles, cleared the needles again after work today, pressure in the filter drops & I can hear the difference in sound.

    As soon as I cleared the pump the pressure in the filter jumped from 10 to 20-15 is the pressure after a backwash.

    I will probably have to backwash in a couple of hours, I will check to see if there is sand coming out when I rinse then.

    My test kit should be here tomorrow or Thursday-then the real questions start


    Thanks again
    I consider myself very lucky I found this site before the pool store found me-pool owner since Nov 2008- Stunningly clear 17,000 gal fiberglass pool, thanks to this site, installed in 1982-24" 3.1sq. ft sta-rite sand filter, 1 hp - 2 speed wisperflo pump-WFDS-4

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    frustratedpoolmom's Avatar
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    Re: Sand in the backwash water & bottom of the pool

    Quote Originally Posted by Bob_Funk

    My test kit should be here tomorrow or Thursday-then the real questions start.
    Thanks again
    Bring it on
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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