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Thread: FC level help

  1. Back To Top    #1

    FC level help

    I want to avoid issue before they happen so I would like some input of what to set my SWG to. This week has been difficult to check everything as I have have been leaving the house at daybreak and not getting home till dark.

    My FC was at 3 last Saturday and I measured it Monday night where FC= 1. My SWG was set at 50% for 10 hrs run time. I bumped it up to 60% same 10 hrs. I tried to measure it early this morning and I believe my reading was about 2.5. I've been using the pink powder method provided in my TF-100.

    Any input or tips is appreciated.

    Other info
    ~15000 gal SW pool
    Water is clear and looks great. (only early morning and night with light on observation)
    temp ~85
    PH = 7.6
    TA = 80
    CH = 190
    CYA = 70
    salt = 3800

    P.S. I would love it if all the test were not red and green related as it is difficult when you are red and green color blind.
    McKinney, TX
    Pool build in progress, 14.8K gallons, OK flagstone copping (sealed), IG Gunite/Pebblesheen (Blue Granite), Pentair intelliflow 3050 vs - svrs, Pentair IC20 Salt-Gen, 60 sq ft Pentair DE filter, 400k BTU Pentair (NG) heater, Polaris 280 with Booster, Dual Time Clocks with freeze protect feature, Pool (1) 500w (1) 100W Spa (1) 100w lights, (2) Skimmers, 4 Pool Returns, 6 Spa Jets, water features incl (3) 12 scuppers on 12 x 31 raised beam, (2) Gushers on tanning ledge, and double cut spa spillway. controlled by easytouch 8
    http://www.troublefreepool.com/under...t56120-40.html

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: FC level help

    Measure the FC level at the same time of day every time, preferably early evening. The FC level will naturally fluctuate through the course of the day. Testing at different times can throw things off because of that.

    It also matters quite a bit how sunny it was. The best days to test are days that have been very bright and sunny. Also, days when you had an unusually large number of people over to swim are not good days for calibrating the percentage.
    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

    Re: FC level help

    Thanks Jason. I understand the effects sun and activity has on FC and measurements as well as trying to be consistant on when to take the measurements. This week is an exception to my norm.

    Let me rephrase my question.

    I am not new to pools, but to SWG, so I would like so advise on settings. how long to run the pump and what percentage. should I start at to try and maintain a good FC level.



    ~1500 gal
    Full sun for ~10 hrs
    IC20 SWG
    McKinney, TX
    Pool build in progress, 14.8K gallons, OK flagstone copping (sealed), IG Gunite/Pebblesheen (Blue Granite), Pentair intelliflow 3050 vs - svrs, Pentair IC20 Salt-Gen, 60 sq ft Pentair DE filter, 400k BTU Pentair (NG) heater, Polaris 280 with Booster, Dual Time Clocks with freeze protect feature, Pool (1) 500w (1) 100W Spa (1) 100w lights, (2) Skimmers, 4 Pool Returns, 6 Spa Jets, water features incl (3) 12 scuppers on 12 x 31 raised beam, (2) Gushers on tanning ledge, and double cut spa spillway. controlled by easytouch 8
    http://www.troublefreepool.com/under...t56120-40.html

  4. Back To Top    #4

    Join Date
    Jun 2011
    Location
    Long Beach, CA
    Posts
    2,670

    Re: FC level help

    If I'm doing the calculations correctly, you are only adding a little over 1 ppm of FC with those settings. To get about 2.5 ppm of FC, you need to run at 100% for 10 hours a day. For a 2.5 ppm raise you need 4.9 oz of chlorine gas. Your SWG can produce 11.2 oz of chlorine in 24 hours running at 100%.

    The chlorine you need for 2.5 ppm a day is calculated this way, 4.9/11.2=.4375. Take this number and multiply it by 24 for hours in a day and you get 10.5 hours of run time at 100% output to generate 2.5 ppm of chlorine for your pool.

    Raise the FC level with bleach to help the SWG for now. You might want to run an OCLT just in case there might be something in there that you can't see.

    The cell you have is on the small side for your pool size.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

  5. Back To Top    #5

    Re: FC level help

    Thanks ping. I'll perform an OCLT
    McKinney, TX
    Pool build in progress, 14.8K gallons, OK flagstone copping (sealed), IG Gunite/Pebblesheen (Blue Granite), Pentair intelliflow 3050 vs - svrs, Pentair IC20 Salt-Gen, 60 sq ft Pentair DE filter, 400k BTU Pentair (NG) heater, Polaris 280 with Booster, Dual Time Clocks with freeze protect feature, Pool (1) 500w (1) 100W Spa (1) 100w lights, (2) Skimmers, 4 Pool Returns, 6 Spa Jets, water features incl (3) 12 scuppers on 12 x 31 raised beam, (2) Gushers on tanning ledge, and double cut spa spillway. controlled by easytouch 8
    http://www.troublefreepool.com/under...t56120-40.html

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