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Thread: FC Dropping too sfter SLAM

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    FC Dropping too sfter SLAM

    I seem to have the opposite problem from all the other threads I found when searching... After my SLAM my FC is dropping incredibly slow.

    Current levels:
    FC 8.5
    CC 0
    PH 7.3
    TA 105
    CH 220
    CYA 20 (estimated)

    A week ago my 2-year-old pooped in the pool and you know how poor swim diapers hold the stuff in. So we cleaned it out and then SLAMed the pool. The one and only time in the past that I SLAMed the pool it took forever for the FC to come back down so I only took it up to 9ppm this time, I know that's lower than it should have been. Since it's an indoor pool I only brought the CYA up to 20ppm and my kit can't measure that so that's based on calculation from the amount of stabilizer I added.

    It has now been a week and my FC has only dropped to 8.5 ppm. I turned off my SWG at the end of the SLAM so that no FC is being added. I know for most outdoor pools the cure is UV from the sun, but for indoor - any recommendations on what to do? What do the huge indoor public pools do that have to regularly elevate their FC for this reason? I've heard that things can be added to neutralize the chlorine such as ammonia, but I'd rather not add other chemicals to my water.

    Thanks!
    15K Gal 12.5' x 36' Gunite Indoor Pool w/ 7' x 7' Spa
    Pentair VF Intelliflo, SWG, Sand Filter, Easytouch8, (3) MagicStream Laminars (1/2 HP SuperFlo, cartridge filter), (10) Savi Note LED Lights
    Coverstar Hydraulic Automatic Cover

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    Mod Squad YippeeSkippy's Avatar
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    Re: FC Dropping too sfter SLAM

    a little pee would make it drop.... hehehehehehe

    Actually, you are in a hard spot when you don't have all that sun UV helping.

    A little hydrogen peroxide will help it along. I forget the formula for how much it takes but you can probably google that or use the search function here to track that down.

    Yippee
    Maddie :) 12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
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    Mod Squad pooldv's Avatar
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    Re: FC Dropping too sfter SLAM

    The quick and dirty rule of thumb is this - the amount in oz of 6% bleach it takes to raise your FC by X ppm's is equal to the amount of 3% H2O2 needed to lower the FC by the same ppm's. That rule of thumb is good to use because it's a lot easier to find 3% peroxide in a drug store and most people use peroxide as an FC lowering chemical in spas where the water volumes are A LOT lower.


    ^^^stolen from Matt
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    Re: FC Dropping too sfter SLAM

    Haha, I was thinking the same thing... We're having some friends over with little kids tomorrow and that just might take care of it Speaking of which, for a CYA of 20 what do people consider too high of FC to swim in??

    A natural solution would be great - I have tried leaving the cover open on two sunny days, but I think with the UV coating on the windows it didn't help - we just ended up with a VERY humid room. I'll search around for some formulas with the hydrogen peroxide - are there any negative effects of using it? I should probably search the forums specifically on that...
    15K Gal 12.5' x 36' Gunite Indoor Pool w/ 7' x 7' Spa
    Pentair VF Intelliflo, SWG, Sand Filter, Easytouch8, (3) MagicStream Laminars (1/2 HP SuperFlo, cartridge filter), (10) Savi Note LED Lights
    Coverstar Hydraulic Automatic Cover

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    Mod Squad pooldv's Avatar
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    Re: FC Dropping too sfter SLAM

    With CYA at 20 it is safe to swim with FC up to 10. It is safe to swim up to shock level for your CYA, FC/CYA Chart

    No, there is nothing negative with hydrogen peroxide.
    TFP Moderator
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    Re: FC Dropping too sfter SLAM

    Thanks, good to know it's safe to swim in. I just hit up PoolMath, and came up with it requiring 171 oz of hydrogen peroxide to drop from 8.5 ppm to my target of 3 ppm (I set my size to 15,000 gallons, punched in 3 as now and 8.5 as target and it says 171 oz of 6% bleach). That's a lot - did I do that right? I could only drop to like 4.5 ppm and let it drop to 3 ppm over time on its own, and that reduces it to 125 ppm. That's still around (8) 16-ounce bottles of hydrogen peroxide! Just want to make sure I'm not figuring this wrong...
    15K Gal 12.5' x 36' Gunite Indoor Pool w/ 7' x 7' Spa
    Pentair VF Intelliflo, SWG, Sand Filter, Easytouch8, (3) MagicStream Laminars (1/2 HP SuperFlo, cartridge filter), (10) Savi Note LED Lights
    Coverstar Hydraulic Automatic Cover

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    Mod Squad pooldv's Avatar
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    Re: FC Dropping too sfter SLAM

    Yes, that is correct. I think some drug stores sell it by the gallon. I would just go swimming and not worry about it. My kids and I swam every day for a week with CYA at 70 and FC at 28 and nobody even noticed.
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