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Thread: After shock...what next?

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    Join Date
    Aug 2011
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    After shock...what next?

    Well, I finally obliterated whatever was growing (water was never even cloudy) but now I have a CYA level of around 40-50, a pH around 7.2 and FC of about 25. I'd like to try and get the FC down to at least close to target before bumping up CYA. And I'm not even sure at what level FC I can even try and figure out what my pH is currently.

    So, some questions I'm hoping you gentle folk can answer for me...

    1. At what FC level can you get a reliable pH reading? I know it's too high now, but how low FC is low enough?
    2. Given I have some CYA in the pool, I don't expect the quick burn off of FC (when we actually get some sun here!). I'll be waiting a while if I want the sun to burn it off, won't I?
    3. I seem to recall if FC is below shock level, you can swim. Is that a good rule of thumb? Or is there a hard number as well that you want to avoid?
    4. I recall reading that you can also use something to lower chlorine. Anyone remember what it is and what else it might affect?
    5. I'm assuming pH needs to be 7.4 or so to swim. If I turned on the deck jets and turned the returns so they shot in the air, any kind of rough idea how fast the pH would raise at around 100TA?
    6. Lastly, there's some junk in the pool that needs to be cleaned. I'd like to throw my dolphin M4 in and let it go to work. But the manual says 4ppm max of Chlorine. Any idea what high chlorine levels would do to it?

    And thanks in advance everyone. This really is an awesome place. I shudder to think where I'd be if there was no TFP and I had to rely on the pool store!
    15,400 gal, 16x32 vinyl rectangle (sport dig), Intelliflo VS, 240 sqft cartridge filter, Intellichlor IC40, Mastertemp 250, Dolphin supreme M4 cleaning, Pentair EasyTouch4

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    Richard320's Avatar
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    Re: After shock...what next?

    Quote Originally Posted by doncaruana
    Well, I finally obliterated whatever was growing (water was never even cloudy) but now I have a CYA level of around 40-50, a pH around 7.2 and FC of about 25. I'd like to try and get the FC down to at least close to target before bumping up CYA. And I'm not even sure at what level FC I can even try and figure out what my pH is currently.

    So, some questions I'm hoping you gentle folk can answer for me...

    1. At what FC level can you get a reliable pH reading? I know it's too high now, but how low FC is low enough? 10
    2. Given I have some CYA in the pool, I don't expect the quick burn off of FC (when we actually get some sun here!). I'll be waiting a while if I want the sun to burn it off, won't I? Yes.
    3. I seem to recall if FC is below shock level, you can swim. Is that a good rule of thumb? Or is there a hard number as well that you want to avoid? It's safe to swim. When I had astronomical CYA, we swam in 22 FC every day
    4. I recall reading that you can also use something to lower chlorine. Anyone remember what it is and what else it might affect? Many things will lower FC - peroxide, thiosulfite, ammonia...it'll drift down without spending any money
    5. I'm assuming pH needs to be 7.4 or so to swim. If I turned on the deck jets and turned the returns so they shot in the air, any kind of rough idea how fast the pH would raise at around 100TA? You don't really know pH with FC so high
    6. Lastly, there's some junk in the pool that needs to be cleaned. I'd like to throw my dolphin M4 in and let it go to work. But the manual says 4ppm max of Chlorine. Any idea what high chlorine levels would do to it? They're assuming the worst - 4 PPM in a fresh fill with no CYA. At shock level for your CYA, you actually have less aggressive FC. I wouldn't hesitate to put it in for a couple hours to let it do its thing.

    And thanks in advance everyone. This really is an awesome place. I shudder to think where I'd be if there was no TFP and I had to rely on the pool store!
    You would have no green in your wallet and lots in your pool
    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
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    Re: After shock...what next?

    Quote Originally Posted by Richard320
    Quote Originally Posted by doncaruana
    5. I'm assuming pH needs to be 7.4 or so to swim. If I turned on the deck jets and turned the returns so they shot in the air, any kind of rough idea how fast the pH would raise at around 100TA? You don't really know pH with FC so high
    I lowered it to 7.2 or 7.1 (color matching not my thing) before I started the shocking a few days ago. Would anything normally raise it? At that low of a level, is it safe to swim?

    Quote Originally Posted by Richard320
    Quote Originally Posted by doncaruana
    And thanks in advance everyone. This really is an awesome place. I shudder to think where I'd be if there was no TFP and I had to rely on the pool store!
    You would have no green in your wallet and lots in your pool
    *That* was literally laugh-out-loud funny!

    Thanks again!
    15,400 gal, 16x32 vinyl rectangle (sport dig), Intelliflo VS, 240 sqft cartridge filter, Intellichlor IC40, Mastertemp 250, Dolphin supreme M4 cleaning, Pentair EasyTouch4

  4. Back To Top    #4
    Smykowski's Avatar
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    Gurnee, IL (North Suburban Chi-town)
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    Re: After shock...what next?

    Low pH is more damaging to equipment than swimmers. At worst, you might get a little eye irritation. Go swimming!
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

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