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Thread: Free chlorine

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    Free chlorine

    My pool was green and after following the green pool instructions, it is turning light milky blue. I am trying to keep it at shock leve. However, when I test the FC level using the TF-100 Test Kit Chlorine Drop test - As soon as I add ONE heaping scoop of the R-870 powder and swirl to mix. The solution turns clear immediately without adding R-871 solution. I used the Chlorine Test (OTO) then the water turns red instead of yellow. I brought it to the pool store, it says the FC level is 5+. Is there anyting wrong with the TF-100 Chlorine Drop test? Thank you.

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    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Free chlorine

    Welcome to TFP!

    There was probably a flash of pink when you added the powder. If the chlorine level is very high, the sample will turn clear as you saw. If you add more powder, it can turn pink/red and then you can use the titrant drops to measure. So just add more powder than just one scoop under these conditions. The extended FAS-DPD test directions here refer to this issue.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  3. Back To Top    #3

    Re: Free chlorine

    Thank you. This is very helpful. Yes, the water turns slightly pink before it turns clear. I did add more powder and it turned pink.

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