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Thread: Testing for FC - Cant get solution totally clear / colorless

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    Testing for FC - Cant get solution totally clear / colorless

    Earlier in the day yesterday by FC was 9.5 and my CC was .5. My CYA was close to 100 (yes, high I know) It was suggested that I might want to shock my pool. I added a jug of chlorine to my pool to attempt to shock it.

    Last night I tried to test for FC using my Taylor kit and I couldn't get the solution to go 'clear'. It would get almost clear but still with a very mild red tint. Typically, the solution will get totally clear / colorless as it's supposed to. I stopped after about 60 drops or so b/c I was affraid I was wasting it. Then I even tried to add the second reagent to turn it back to pink again and it wouldn't go even after several drops.

    The same thing happened again this morning. This time I got up to almost 70 drops and it wouldn't go totally colorless.

    I've been using the 10ml sample (1 drop = .5ppm increments)

    What exactly is happening here and is it a problem or am I just no doing somthing right?

    Thanks in advance!!!

    TFP SUPPORTER through TFTestKits.com - My Pool: South Florida, 11K gallons, In ground, concrete / Diamond Brite, Free Form with attached spa (no heater- go figure) Built around 1998, original surface, Jacuzzi Magnum Force 1.5HP pump, Jacuzzi Cartridge Filter, Rainbow 320 Tablet Feeder, Hayward Navigator Pro, Taylor K-2006 w/ TFTestKits replacemeng Reagents.

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    duraleigh's Avatar
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    Re: Testing for FC - Cant get solution totally clear / colorless

    When does the color change stop? That's the endpoint of the test.

    You should read "How to Shock your Pool" in Pool School and also the CYA/chlorine chart.

    Sorry to be very blunt but you are wasting your time trying to shock that pool with 1 jug of Clorox. You need 5 gallons just to get to 25ppm and then probably at least that much again to complete the shock process.

    The only way out of all that chlorine is if you commit to partially draining and refilling to get your CYA down around 50ppm
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Testing for FC - Cant get solution totally clear / colorless

    Quote Originally Posted by duraleigh
    When does the color change stop? That's the endpoint of the test.

    You should read "How to Shock your Pool" in Pool School and also the CYA/chlorine chart.

    Sorry to be very blunt but you are wasting your time trying to shock that pool with 1 jug of Clorox. You need 5 gallons just to get to 25ppm and then probably at least that much again to complete the shock process.

    The only way out of all that chlorine is if you commit to partially draining and refilling to get your CYA down around 50ppm
    The color change stops around 54 drops. That would indicate a ph of around 27 if the solution was colorless. I believe that's also approaching shock levels of chlorine according to the CYA chart.
    TFP SUPPORTER through TFTestKits.com - My Pool: South Florida, 11K gallons, In ground, concrete / Diamond Brite, Free Form with attached spa (no heater- go figure) Built around 1998, original surface, Jacuzzi Magnum Force 1.5HP pump, Jacuzzi Cartridge Filter, Rainbow 320 Tablet Feeder, Hayward Navigator Pro, Taylor K-2006 w/ TFTestKits replacemeng Reagents.

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    JasonLion's Avatar
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    Re: Testing for FC - Cant get solution totally clear / colorless

    You may have an extremely high FC level and not be using enough of the powder to start with. That would cause the pink color to be very faint. Another possibility is that when the sample turns almost clear you are done and the very slight pink is being caused by some contamination. Try adding triple the amount of powder to start with and see if that changes anything.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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