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Thread: Not sure how to interpret these numbers

  1. Back To Top    #1
    Captain 776's Avatar
    Join Date
    May 2016

    Not sure how to interpret these numbers

    Under the Suggested FC Levels it has the values, what do they mean ??

    SWG: 2 Normal 4 to 8 Shock: 20 Mustard Algae Shock: 29

    I get my Targets from TFP.

    My FC is 13 and my Target shows as 8.........but pool math doesn't say to do anything. I should just leave it alone? My SWG is on Max and running 7 hrs a day. Unless otherwise advised, I will turn down my SWG % and lessen my run time by an hour or 2?
    Sound correct ?
    CC is .5
    The rest I understand and is easily manageable.
    I was gone to America for 5 weeks and my maid added one bag of salt while I was gone and ran the robot every day but I surely didn't want her messing with chemicals.

    My water is still crystal clear, s always.

    Thanks for your always

    8M x 4M X 2M no slope IG CONCRETE w/ceramic glass tile
    17,000 Gal EMAUX SWG JAZZI FILTER W/1-3 mm glass media, Jazzi Multi-port valve with
    T-750 filter w/ glass media
    1 main drain sump -3 returns - 1 skimmer
    Kokido digital salinity tester, Kokida drops for CL Hanna digital PH meter, Taylor K-2006

  2. Back To Top    #2

    Chasmengr's Avatar
    Join Date
    May 2016
    Omaha, NE

    Re: Not sure how to interpret these numbers

    Values are concentrations expressed in ppm (parts per million; milliliters per cubic meter).

    Higher FC concentrations are required for higher CYA concentrations.

    Once you know your CYA ppm, the chart linked above shows three FC ppm: minimum to avoid starting biological growth(s) (e.g., algae), target to aim for when you add liquid chlorine if your SWG isn't maintaining minimum (allowing you to adjust your SWG output to achieve minimum), and shock value if you end up with biological growth and have to SLAM.

    So before using PoolMath, read the linked chart to identify your targets (enter into "Target" column in PoolMath). Enter your test results in the "Now" column, and PoolMath will tell you what to add to go from your now/test value to your target value.

    In your case your test value for FC (13) is greater than your target value (8), so PoolMath finds nothing to do.

    The most critical number in PoolMath is "Size _____ gallons." Everything in PoolMath is based on your pool's water volume; be as accurate as possible.

    Determine your salt ppm to ensure it's in desired range published by your SWG instructions.

    IMO this part of PoolMath is outdated, and should be ignored. Use the linked CYA/FC chart instead:

    Confirm your CYA concentration; I'm guessing you can turn down your SWG significantly.
    Chas & Cheryl (first-time, third-year pool owners)
    Radiant Metric Oval AGP 16'x32'x52"; Pentair: Clean&Clear 150 Cartridge, OptiFlo 1.5 Hp 2-spd, and 320C Feeder (all mounted below water level); Taylor K-2006 & SpeedStir; Maytronics Dolphin E10 (aka Einstein)
    installation pics (2015-2016)

  3. Back To Top    #3
    Isaac-1's Avatar
    Join Date
    May 2010
    SW Louisiana

    Re: Not sure how to interpret these numbers

    If you are having to run your SWG at 100% 24x7 it is likely either way undersized, or you have something consuming your FC, you might want to do an overnight chlorine loss test to confirm an issue. Pool School - Perform the Overnight FC Loss Test (OCLT)
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
    I use and endorse TFtestKits TF-100 from
    ~Remember TFP counts on your donations to keep this site ad free~

  4. Back To Top    #4

    TFP Guide
    GaryT58's Avatar
    Join Date
    Jul 2016
    Monroe, GA

    Re: Not sure how to interpret these numbers

    The pool math is basically assuming you are using liquid chlorine. So to reduce from 13 to 8, you don't add any more and wait for it to reduce. Since you have a SWG, you would want to turn down the %age and/or run time.
    38'x16' Fiberglass pool - 3.5' - 8' deep - 19,000 gallons. AutoPilot Total Control SWG (RC-52 cell), Pentair SuperFlo VS, Pentair SD70 Sand Filter, Coverstar Automatic Cover, 10' board, PAL Treo lighting, Polaris 9550 Sport robot, Lamotte ColorQ Pro 7 test kit.

  5. Back To Top    #5

    Join Date
    May 2015
    Land O Lakes, FL

    Re: Not sure how to interpret these numbers

    What model of EMAUX SWG do you have?

    This page shows the output of each model.
    2016 Pool Build: 12k IG Blue Granite Pebblesheen, Travertine Coping & Pavers, Pentair IntelliFlo, Intellichlor, Easytouch, Clean & Clear 320, Heliocol Solar - TF-100 test kit w/ SpeedStir
    SWG Run Time Calculator

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