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Thread: Can Phos-free be used in lieu of shock?

  1. Back To Top    #1

    Join Date
    Jun 2011
    Austin, Texas

    Can Phos-free be used in lieu of shock?

    Today I was at my pool store picking up a repaired pump motor, and I told the guy that I have a salt pool, but the chlorine level is zero, because my pump has been broken the last several days. I asked him if in this situation, should I throw in some powdered shock to get the chlorine level up.

    He said I could, but that he more highly recommends I use Phos-Free instead of shock, and then just set my generator on the normal automatic setting, and the chlorine level will gradually return to normal.

    He goes on to say I should add one capful of this phos-free each week.

    My question is: if I don't shock the pool, I think it will take a while for the chlorine level to reach normal level, but the pool employee seems to think that by tomorrow it will be safe to swim in it, because I've just added this phos-free chemical. Even though the chlorine level will likely still be at a low level tomorrow. Is he right?
    18 foot diameter, 52" tall above ground Cornelius pool, with vinyl liner, and resin wall caps.
    Roughly 7600 gallons
    Blue Wave "Sandman" Sand filter/pump, model NE6150. Pump is 1 HP
    Intex SWG, model # 54601E

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

    Re: Can Phos-free be used in lieu of shock?

    No, he is not.

    While phos-free may keep algae from feeding and growing, it will not kill bacteria. Phos-free is not a sanitizer, chlorine is. Head straight for How to Shock your Pool and follow the directions. Not all that hard to do, just requires diligence. You aren't green yet, so it shouldn't take but a day or two to restore the sparkle.
    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!

  3. Back To Top    #3

    Join Date
    Feb 2008
    Flower Mound, TX

    Re: Can Phos-free be used in lieu of shock?

    UGH!! Man, I get so tired of these pool store chumps pushing Phos-free on folks. Phos-free and chlorine are not the same. There is no reason under the sun for you to need Phos-free, even if you had a big block of elemental phosphorus sitting at the bottom of the pool.

    Since your pump has been out, you will likely need to shock your pool. You can use plain old unscented household bleach for this purpose. Read the following link for starters...


    Stick with us and we will get your pool looking right. You will also be able to keep your money rather than having the pool store drain your wallet on stuff you (and nobody else) needs.
    10K gallon IG gunite with waterfall; Pentair CC320P filter; WhisperFlo 2 HP pump
    TF Test Kits - Pool Math - Pool School
    "It depends."- JohnT

  4. Back To Top    #4

    Re: Can Phos-free be used in lieu of shock?

    A lot of pool guys I know are dead-set on using these as well... so set, that Phosphate removers are now a "religion". The belief is as strong as any other type of religion, and you'll never convince a true believer: I've had several tell me that it's now the first thing they add to every pool, and why organic-loaded green-cleans take so long (and why it's the first thing that should be added to a swamp - ahead of chlorine).

    I have yet to find a need for it, and I do a lot of G2Cs.
    ~45Kg Pool with attached Spa, NSP-72 DE, Minmax 400 Heater, Tahoe Blue Pebbletech, Jandy SWG via Aqualink RS-8, The Pool Cleaner (black)
    Pumps: X3 Hybrid Pump (switches to SPA), 2HP Spa (additional, when SPA is on), and a 1HP For Waterfall
    8, 4x12 Solar Panels on the roof of the pool-house (~12' up)

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