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Thread: Can topping off affect FC Level

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    Can topping off affect FC Level

    If I did the FC test and then filled up and topped off the pool, could this affect my FC level and drop it? I assume it can because I have tested my top off and it has not FC in it and 1-1.5 CC in it.

    Thanks.
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    Butterfly's Avatar
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    Re: Can topping off affect FC Level

    Quote Originally Posted by mynewpool
    If I did the FC test and then filled up and topped off the pool, could this affect my FC level and drop it? I assume it can because I have tested my top off and it has not FC in it and 1-1.5 CC in it.

    Thanks.
    How long did you circulate before testing?

    Possible testing error. Suggest you circulate some more and retest.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    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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  3. Back To Top    #3

    Re: Can topping off affect FC Level

    Yes of course it will. It's expressed as parts per million of the water ..so if you add water you are diluting the chlorine.
    Glenn - Pickering, Ontario
    Circa 1980 Vinyl In-ground 80,000 Ltrs. ~ K2006 Kit ~ Hayward Pump/Navigator/Sand Filter ~ Raypak 255 Gas Heater

  4. Back To Top    #4

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    Re: Can topping off affect FC Level

    Quote Originally Posted by Butterfly
    Quote Originally Posted by mynewpool
    If I did the FC test and then filled up and topped off the pool, could this affect my FC level and drop it? I assume it can because I have tested my top off and it has not FC in it and 1-1.5 CC in it.

    Thanks.
    How long did you circulate before testing?

    Possible testing error. Suggest you circulate some more and retest.
    No error in testing. I tested last night and had an FC level of 3.5. I topped off the pool but did not test again. Pump was running all night and when I tested this morning to add bleach I got a result of 2.5. Typically I lose .5-0 overnight, usually 0 in most cases unless it was really windy or a lot of rain put dirt in the pool. So that is why I was asking. The person above me answered my question though.

    Thanks.
    13,000 Plaster IG Pool approx
    Hayward C5030 Cart Filter
    Emerson 1081 EB653 1.0 HP 1.40 S.F. 3450 RPM
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    Butterfly's Avatar
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    Re: Can topping off affect FC Level

    Sorry, mnp, I misunderstood your post.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    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.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  6. Back To Top    #6

    Re: Can topping off affect FC Level

    Do a search on "chloramine" to see a recent discussion in post titled "pre-algaed water" or something like that.

    The tap water is treated with chloramine rather than just chlorine, that is what appears as CC on the test of tap water. It is more stable than chlorine for muni water needs. So it comes with a mix of ammonia and chlorine from the tap, as chloramine. Chem Geek said, if I understood correctly, that the chloramine will consume some FC to eliminate the ammonia part. So, if you added rather a lot of tap water compared to the pool size, you might see that effect.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

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