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Thread: FC Levels? Am I doing this right?

  1. Back To Top    #1
    ateam's Avatar
    Join Date
    Jul 2015
    San Antonio, TX

    FC Levels? Am I doing this right?

    I'm pretty new to TFP and I think I'm starting to pick it up, but I was hoping to get some confirmation on some of my assumptions.

    First things first, my water looks beautiful.

    My test results (using TF-100)
    PH - 7.5
    CC - 0.5
    TA - 100
    CH - 300
    CYA - 50
    Borates - 30

    According to the chlorine/cya chart my FC min is 4 and my target is 6.

    I'm struggling with FC levels. I'm assuming I don't want my FC to drop below 6 (target level). I've been adding bleach to get up to 10-10.5 every night, but I'm dropping down to 5-5.5 by the end of the day. I'm not sure if I should be worried or not because I am dropping a little below the target, but staying above the min.

    I know I have a couple things working against me:
    bather load = 4 kids, wife and me, plus 2 golden retrievers (and sometimes the neighbors as well)
    sun = South Texas (I do get some shade, but it's been extremely hot and sunny lately)

    One of my dogs has a really bad habit of getting wet and then rolling in the mud before going for another swim, so I'm sure that isn't helping either.

    Right now I'm adding a full jug of bleach every night to replenish the ~5 FC of chlorine lost each day. This feels a little excessive to me, but maybe my expectations are off.

    Should I just get used to adding a jug or more of bleach every day? Do I need to raise my FC levels a little bit to make sure I don't go below 6 each night, or would I just be wasting bleach?

    in-ground pool/spa with spill over, plaster/pebble, multiple waterfalls
    4x Pentair pumps, Pentair DE filter, Pentair Heater, Auto-fill
    Completed 2011, TF-100 test kit w/ Speedstir

  2. Back To Top    #2

    Join Date
    Aug 2014
    Northern IL

    Re: FC Levels? Am I doing this right?

    Hmmm. I think you should raise that target so you don't dip below.

    Texans will chime in here, but I am thinking you may want to raise your CYA, but an OCLT first to reassure yourself that you have no need to slam? Thinking out loud...

  3. Back To Top    #3
    Mod Squad woodyp's Avatar
    Join Date
    Apr 2010
    East Texas

    Re: FC Levels? Am I doing this right?

    That minimum# is the one you don't wanna go below. My pool still loses 4 ppm FC daily with a cya of 60------full sun all day. My minimum # is 5 so I take it to 9---to 9.5 nightly. I really should try a cya of 70 or so. ALWAYS more before a good bather load and afterwards as well. Adding anything much over what your daily loss is excess. That much extra "unprotected" by cya will disappear rapidly.
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
    Pool Rover Jr., Pool Blaster Max, Diver Dave TF100 Test Kit/Speed Stir
    Margaritaville Frozen Concoction Maker, Liqour Chiller, & Drink Mixer & Party Tub----Collect 'um all!

  4. Back To Top    #4

    Join Date
    May 2015
    Chickasha, OK

    Re: FC Levels? Am I doing this right?

    Definitely take your FC up to somewhere north of 10.0 tonight (test, add, wait 30 minutes with pump running, then test again to be sure) and do an OCLT. Just because your CC is 0.5 doesn't necessarily mean you're not fending off some sort of growth.

    If you pass the OCLT, my recommendation is to test your FC in the morning, before the sun comes up, and then in the evening, after the sun has gone down, and figure out what your FC loss due to sunlight is. Then bump your target FC high enough that you don't drop below the minimum FC for your CYA level before the sun goes down.

    I have kept my CYA at 40 ppm all summer (finally trying to get it up a bit), which makes my Minimum FC 3, and my Target FC 5. Since my pool loses 2.0-2.5 ppm FC daily (full sun all day), I have bumped my target to 6.0, just to make sure I don't go below 3.0 before I get home to add more chlorine.
    25,000 gallon freeform gunnite/plaster, built in the 1970s/80s; Sta-Rite 9463004 575-lb. sand filter; Sta-Rite DuraGlas/Max-E-Glas (P2RA5F-125L) single-speed 1.5 HP pump, manufactured 12/1993 (1M93M).
    Helpful links: TFTestKits; Pool School; ABCs of Pool Water Chemistry; Chlorine/CYA Chart; PoolMath; SLAM - Shock Level And Maintain

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