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Thread: Sand filter pressure goes high shortly after backwash

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    Join Date
    Jun 2015
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    Merrick, NY
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    Sand filter pressure goes high shortly after backwash

    Hi All,
    Having a rough time this season so far. Pool was opened and proper chemicals added, NOT VACCUUMED (lots of leaves on floor). Water got clear in hours. Heater turned on. Two days later the heater somehow caught fire and whole front-end melted - landscaper saw the fire and extinguished. Doesn't seem like it was a gas fire. While heater shopping, I didn't bother with chemicals or vaccuuming - water went very cloudy and light green. New heater installed and chemicals brought back up to par, confirmed via water test performed by Leslie's. Water got clear but stayed HIGHLY cloudy. Shock added, no clearing of cloudiness. Filter runniing about 24 so backwashed and it came down to about 16 and Returns pressure was restored. One day later, still highly cloudy. Pressure went back to mid-20's so I backwashed again. Again, down to 16. Clarifier added - no luck. DE added - no luck. Still very cloudy. I'm now playing yo-yo games with the filter.... it goes up to mid 20's, I backwash, it goes down to about 16, then it goes back up few hours later.
    Does this yo-yo'ing of the pressure mean it's time to replace sand? That's the only thing I can think of. Originally I thought maybe the fire's soot was being pushed into the pool, but now even with the new heater, same thing.
    All help will be appreciated tremendously... very frustrated at this point.
    Thanks!



    Inground pool, chlorine, approx 12k gallons, sand filter, hayward ng heater: new, 2 skimmer baskets, no main drain, hayward superpump: new last season

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    Mod Squad JohnT's Avatar
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    Apr 2007
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    SW Indiana
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    Re: Sand filter pressure goes high shortly after backwash

    Welcome to TFP!

    The rising pressure shows your filter is doing its job. Seems like a bit of a short cycle though. Are you backwashing for at least 3 minutes? If not, try that and see if the filter runs longer before needing backwashing again.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    ship of fools's Avatar
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    Nov 2011
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    Albany, NY
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    495

    Re: Sand filter pressure goes high shortly after backwash

    X2 on the filter doing its' job.

    Sounds like you have algae, it is getting killed and filtered out.

    I may as well be the one to say it ..... in order for us to help we really need you to post a full set of test results from a reliable test kit (not Leslies results). Get a kit, post the results and get ready to go swimming!
    21,000 gallon inground
    Haywood Sand Filter
    Vinyl Liner

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    Jun 2015
    Location
    Merrick, NY
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    Re: Sand filter pressure goes high shortly after backwash

    Thank you for your reply… And a few of the times that I back washed, it was not for a full three minutes, but other times it was actually more than that for the glass jar showed clear water. After backwashing for about four minutes, I rinsed for four minutes as well.

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    Jun 2015
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    Merrick, NY
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    Re: Sand filter pressure goes high shortly after backwash

    Hi… Is there a specific test you can recommend? I thought Leslie's was a pretty thorough test.

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    Charlie_R's Avatar
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    May 2013
    Location
    Mexico, MO
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    2,156

    Re: Sand filter pressure goes high shortly after backwash

    We recommend the TF-100 or Taylor K-2006. Neither are available at your local pool store, you must order online.

    See the article in Pool School for a comparison of test kits.

    The TF-100 or K-2006 can be ordered from TFTestkits.net, Amazon carries the K-2006.
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

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    duraleigh's Avatar
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    Apr 2007
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    Sebring, Florida
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    Re: Sand filter pressure goes high shortly after backwash

    Hi… Is there a specific test you can recommend? I thought Leslie's was a pretty thorough test.
    Pool Store testing is simply not accurate or dependable. We advocate your own testing because no one will take care of your pool as well as you do. Leslie's goal is to sell you something each time and our goal is to teach you something each time.

    You can read the hundreds of stories here about pool store testing and the amazing successes people have when they take charge of managing their own pool water.....it is eye opening.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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