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Thread: Free Chlorine Higher than Total Chlorine

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    Darko5500's Avatar
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    Free Chlorine Higher than Total Chlorine

    Is it normal that FC is higher than TC? My test results are:

    FC=5.3
    TC=5.0
    PH=7.4
    CH=250
    CY=100
    TA= 100

    I have just started to move away from pool shop measurements and adopted the BBB method as discussed in forums here.
    I use a Milwaukee MI413 Photometer for the Chlorine check and a basic Taylor test kit for TA and PH. My CYA and CH is done via a strip test at my local pool shop, so reliability is questionable. I have only been a pool owner for 12 months but my pool is roughly 20 y.o.

    Cheers,
    D.
    Pebble 63kL - Waterco S602 (Zeolite) - Hurlcon EVO P300 3 sp 1KW.
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    Spa - spill over (no heater at the moment).

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    BoDarville's Avatar
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    Re: Free Chlorine Higher than Total Chlorine

    Quote Originally Posted by Darko5500
    Is it normal that FC is higher than TC?
    No. FC can only be equal to or less than TC. FC+CC=TC
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    Re: Free Chlorine Higher than Total Chlorine

    Welcome to the forum!

    Not familiar with your machine, but that is a minor test error or variation. You should have a TC of 5.3 if there is no Combined Chlorine. What you don't want is your TC to be more than your FC by more than 0.5 Ideally.

    Free + Combined= Total.

    Your CYA is high at 100 and might be more than that. Not good, because it requires you to have a high FC level to be effective. See the links in my sig line and start reading the ABC's.
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    Darko5500's Avatar
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    Re: Free Chlorine Higher than Total Chlorine

    Thanks BoDarville. What do you suggest I do in regards to measurement? The photometer is brand new and seems far more accurate than my local pool shop. The basic Taylor kit I have also reads 5 for TC.
    Pebble 63kL - Waterco S602 (Zeolite) - Hurlcon EVO P300 3 sp 1KW.
    Watermaid SWG QT150 cell - Polaris 280 Cleaner.
    Spa - spill over (no heater at the moment).

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    Darko5500's Avatar
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    Free Chlorine Higher than Total Chlorine

    Thanks Brushpup, I will follow the links. I have been reading up on the some of the basic water testing procedures here and am looking to further my knowledge. I should mention that the photometer reads in mg/l which is nigh on the same as ppm.

    I think the Cya is wrong anyway as I have drained some water from the pool and topped back up with fresh fill. This measurement was taken prior to the drain and the previous test at the same shop showed 80.
    Pebble 63kL - Waterco S602 (Zeolite) - Hurlcon EVO P300 3 sp 1KW.
    Watermaid SWG QT150 cell - Polaris 280 Cleaner.
    Spa - spill over (no heater at the moment).

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    Re: Free Chlorine Higher than Total Chlorine

    Just curious, do you know the range capability of the photometer? Ones I am familiar with usually top out at 10 or less without sample dilution. I think 5 is the top end of that particular Taylor kit, but I stand to be corrected on that. If you can get Taylor stuff down under, you ought to get one of their FAS/DPD kits for FC.

    You are correct about the mg/L conversion, yes.
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    Darko5500's Avatar
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    Re: Free Chlorine Higher than Total Chlorine

    This Milwaukee meter does top out at 10mg/l and the Taylor at 5. I am definitely keen to get a better Taylor test kit but one of the distributors down here has stopped importing them.
    Pebble 63kL - Waterco S602 (Zeolite) - Hurlcon EVO P300 3 sp 1KW.
    Watermaid SWG QT150 cell - Polaris 280 Cleaner.
    Spa - spill over (no heater at the moment).

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    Re: Free Chlorine Higher than Total Chlorine

    You might still check with some to see if there are any left. I'm just not familiar with shipping stuff down there or I would have the perfect solution for you. We like TFtestkits.net, but you will have to ask them about overseas shipping. I presume lots of problems getting chems into another country, but I just don't know.
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    Re: Free Chlorine Higher than Total Chlorine

    Quote Originally Posted by Darko5500
    What do you suggest I do in regards to measurement?
    Honestly, I'm not familiar with that testing instrument. If there is any way you can get a FAS-DPD chlorine test, I would suggest that.

    Quote Originally Posted by Darko5500
    CY=100
    I'm assuming this is CYA. As you have already pointed out, I would also be suspect of the accuracy of the results since they came from pool store test strips. If you can get a CYA test that uses reagent R-0013, I would do so and then retest. If not, then your current results are all we have to go on. If that's the case, I would drain 50-60% of your pool water and refill as this is the only way to reduce CYA.

    The chlorine / CYA relationship is a cornerstone of pool water management. Understanding this will help you avoid the majority of problems that plague many pool owners. Take a look at the Chlorine CYA Chart.
    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
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    Re: Free Chlorine Higher than Total Chlorine

    Thanks for all the tips. I did see that CYA chart which is what led me to submit this post. I will see if I can find a more reliable test for CYA and then repost. Might take a while to source though.
    Pebble 63kL - Waterco S602 (Zeolite) - Hurlcon EVO P300 3 sp 1KW.
    Watermaid SWG QT150 cell - Polaris 280 Cleaner.
    Spa - spill over (no heater at the moment).

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    Darko5500's Avatar
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    Re: Free Chlorine Higher than Total Chlorine

    Hi Guys, finally managed to import a Taylor k2006 kit into Oz. here are my readings;

    TA 90
    pH 7.6
    CH 260
    CYA 80
    FC 8.5
    CC 0.5

    My Martini Instruments Photometer shows FC 7.8 and TC 7.8.

    Pretty happy with the overall results. Guess I need to drop the CYA level and then I'll be able to adjust the FC down a little.

    Cheers,
    D.
    Pebble 63kL - Waterco S602 (Zeolite) - Hurlcon EVO P300 3 sp 1KW.
    Watermaid SWG QT150 cell - Polaris 280 Cleaner.
    Spa - spill over (no heater at the moment).

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    Re: Free Chlorine Higher than Total Chlorine

    Sounds like a plan to me. Not bad readings from the machine on FC. As for the CC number....not so sure about that one. Weird.
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    Darko5500's Avatar
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    Re: Free Chlorine Higher than Total Chlorine

    Thanks Brushpup. I'm getting more consistent readings with the photometer. It pretty much always shows the TC the same or slightly higher than the FC now. The first couple of weeks using it it always showed FC higher. Must have been inconsistent with my testing methodology.
    Pebble 63kL - Waterco S602 (Zeolite) - Hurlcon EVO P300 3 sp 1KW.
    Watermaid SWG QT150 cell - Polaris 280 Cleaner.
    Spa - spill over (no heater at the moment).

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    Patrick_B's Avatar
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    Re: Free Chlorine Higher than Total Chlorine

    Sure thing......

    Maybe it is method...something you are missing or not doing with the right timing. Photometers I have used, normally read FC immediately, and
    the TC takes a 3 minute cook time before reading. Something seems amiss. Still, 7.8 FC compared to 8.5 titrating for FC ain't too shabby.
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    Darko5500's Avatar
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    Re: Free Chlorine Higher than Total Chlorine

    Agree it must be in the timing. The instructions say to wait 2mins 30sec.
    Pebble 63kL - Waterco S602 (Zeolite) - Hurlcon EVO P300 3 sp 1KW.
    Watermaid SWG QT150 cell - Polaris 280 Cleaner.
    Spa - spill over (no heater at the moment).

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    linen's Avatar
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    Re: Free Chlorine Higher than Total Chlorine

    No need to drop the cya level since you are using a swg. Our recommended range is 70-80 ppm cya: http://www.troublefreepool.com/pool-...ater_generator
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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