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Thread: FC much higher than TC

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    FC much higher than TC

    I'm seeing an issue where my FC is much higher than my TC. PH levels are good and CYA is around 35. However, FC is around 10 and TC is around 2.
    This was tested with 2 different brand of strips (I know...) and chemistry is not with BBB. Chlorine is typically added via 3" puck (calcium-based if I recall correctly) in the skimmer. Pool details are in sig. I'm trying to understand how FC can be higher than TC and what I should do about it.
    Intex 15x36 Easy Set (2,800 g.)
    Intex 16" 2650 gph sand filter/pump combo & SWCG
    Intex 800 gph filter just for the surface skimmer

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    Mod Squad JohnT's Avatar
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    Re: FC much higher than TC

    Can't be. FC+CC=TC, so FC will always be less than or equal to TC.
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    Re: FC much higher than TC

    Exactly what I thought with my, at this time, very limited knowledge.
    Still both strips (different brands) showed the same thing.
    Intex 15x36 Easy Set (2,800 g.)
    Intex 16" 2650 gph sand filter/pump combo & SWCG
    Intex 800 gph filter just for the surface skimmer

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    Re: FC much higher than TC

    Quote Originally Posted by George_
    I'm seeing an issue where my FC is much higher than my TC. PH levels are good and CYA is around 35. However, FC is around 10 and TC is around 2.
    This was tested with 2 different brand of strips (I know...) and chemistry is not with BBB. Chlorine is typically added via 3" puck (calcium-based if I recall correctly) in the skimmer. Pool details are in sig. I'm trying to understand how FC can be higher than TC and what I should do about it.
    How did you measure your FC and TC?

    FC - Free Chlorine
    CC - Combined Chlorine
    TC - Total Chlorine

    TC = FC + CC

    Your TC will always be equal to FC (if you have no CC) or more than FC (if CC is present in the water)
    76549 Liters -- Cartridge Filter -- In Ground -- Vinyl -- TF-100 Test Kit -- AquaVac Robotic Cleaner -- UV Sanitation -- Winter Safety Cover -- Installed 2010 -- Southwestern Ontario, Canada

    Latest Test Results June 25:
    FC - 6, CC - 0, CYA - 40, CH - 110, TA - 90, pH - 7.5

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    Re: FC much higher than TC

    If the strips claim FC>TC, then they're not testing what they claim to be testing. Kind of like a calculator that claims 1+1=5 - if the tool gives a result which is wrong by definition, the fault is in the tool, not reality.
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    frogabog's Avatar
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    Re: FC much higher than TC

    Darn strips! puke (where's the puke emoticon anyway? lol)
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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    Re: FC much higher than TC

    Maybe your FC is 10 and your CC is 2 and TC is 12
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    Re: FC much higher than TC

    Quote Originally Posted by George_
    Exactly what I thought with my, at this time, very limited knowledge.
    Still both strips (different brands) showed the same thing.
    Hi George, I'd say both strips are wrong. Strips are very inaccurate for testing your pool.

    Do yourself a favor and get one of the recommended kits. See Test Kit comparison in Pool School.

    In the interim, you could take a water sample to a pool store.
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    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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    Re: FC much higher than TC

    I guess it's possible it should have been labeled CC and not TC on the chart. Other than that....I don't know.
    Intex 15x36 Easy Set (2,800 g.)
    Intex 16" 2650 gph sand filter/pump combo & SWCG
    Intex 800 gph filter just for the surface skimmer

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    Mod Squad JohnT's Avatar
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    Re: FC much higher than TC

    Quote Originally Posted by frogabog
    Darn strips! puke (where's the puke emoticon anyway? lol)
    Here
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    frogabog's Avatar
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    Re: FC much higher than TC

    LMAO... that's a fast puke (and thick!)

    I wanna puke that fast. Gotta remember to eat before I drink beer perhaps...
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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