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Thread: SWG not producing more chlorine when I crank it up

  1. Back To Top    #1

    Join Date
    Jan 2010
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    Northern Virginia
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    282

    SWG not producing more chlorine when I crank it up

    This is my second season with the (newly built) pool. Last year I had my SWG set to 35-40% or so and had good chlorine numbers (1-1.5 or so) and clear water. This year my chlorine numbers have been between .5 and 1.0 and each time I get a reading like that, I bump up my SWG run time, but the chlorine numbers don't seem to change. Here are some numbers:

    Salt percentage - 3.3

    June 3 - SWG 40% - FC 1
    June 10 -SWG 45% - FC 1
    June 17 -SWG 55% - FC 1
    June 23 -SWG 65% - FC 1
    July 1 - SWG 80% - FC 1
    July 9 - SWG 80% - FC .5
    July 12 - SWG 85% - FC .5

    Other numbers from last weekend:

    ph 7.5
    T/A 90
    CH 550
    CYA 80

    Pump run time - was 12 hours, now 13 hours.

    Any idea what's going on here? I'm more than double than I was last year and I'm not maintaining the same levels of chlorine.

    One other data point - during one of my low chlorine spells, I did a shock with bleach, but I don't think I turned the SWG off. Could this have ruined the cell?

    Thanks!
    Bart
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

  2. Back To Top    #2
    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: SWG not producing more chlorine when I crank it up

    You probably have a low level algae problem. You should do an over night FC loss test, which will most likely indicate a need to shock the pool.
    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
    Jan 2010
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    Northern Virginia
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    Re: SWG not producing more chlorine when I crank it up

    I don't understand. Would algae in the pool prevent the SWG from working properly?

    Also, if I shock with bleach, I need to turn off the SWG, correct? How long do I need to leave it off?

    Thanks!
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

  4. Back To Top    #4
    elwood58's Avatar
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    May 2012
    Location
    Sun City West Arizona (2nd Home)
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    639

    Re: SWG not producing more chlorine when I crank it up

    I could make a few possible assumptions based on your test results, and other comments included in your post.

    1. Your CH is on the high side, which could contribute to scaling on the Salt Cell in your SWG. I would at least do a cleaning of the cell.
    2. You do not list CC in your test results, but I assume it may be higher than 1, and means you may have organics developing that will eat all of your chlorine.
    3. I assume your run time is primarily during daylight hours? If not, the time you choose to test FC will be important.
    4. I assume your salt reading is in ppt and not ppm, so 3300, which should keep most cells happy.

    As far as turning the SWG off during shock, I do it to save cell life and electricity, but am not under the impression that it would actually harm my cell. It is just redundant in the face of shock levels of FC.
    19204 Gallon L Shape with a 10X10 2nd Step Baja Ledge. Intellichlor IC-40, IntellipH, Cartridge Filter, Pentair Heater/Chiller (Heat Pump). Tons of Deck with Deck Jets. Construction Complete 6/5/17.

    "If you don't measure it, you can't manage it!"

  5. Back To Top    #5

    Join Date
    Jan 2010
    Location
    Northern Virginia
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    282

    Re: SWG not producing more chlorine when I crank it up

    Thanks elwood!

    I had a massive scale problem when I opened the pool and beat it back with 2 no-drain acid washes. Do you think that could be a factor here? Did the scale get removed from the pool, but not the SWG itself?

    Thanks again,
    Bart
    700 sq. ft./30,000 gal, gunite pool; 48 SF DE filter; 1.5 HP pump; Salt Water Generator; Solar Heat

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