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Thread: Help with Fas-dpd test results

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    Help with Fas-dpd test results

    Woops this was supposed to be a response not a new thread.

    When I do a FAs-dpd test on my father inlaws pool, after I add the powder abd get the water to turn clear, I go to add the reagent and by the time I pick the bottle up, it is already turning pink again.


    I was hoping to find someone else that this has happened to. Except mine turn's back to pink much faster. I get my 10cc of pool water add my powder, water turns pink I add the drops and get to clear counting the drops. Then I set the bottle down and pick up the reagent, by this time the water is already turning pink again, and when I add the reagent, it really goes to pink. I know doubt have CC issues, but I am still not very confident in my result's. This is on my father inlaws pool, 24,000 inground vinyl liner, using tablets. This was the first winter he used the safety cover, and it let a ton of junk in there. When he told me he needed help, it took me 4 days, with constant circulation, and 3 gallons of liquid Cl a day to get the CC under control, begining to look great now!!!

    Thanks to all, for all the great info on this site.
    17,000 gallon IG Humpback Kidney
    333k Sta-Rite Max-e-therm Heater
    Sta-Rite Modular Filter
    Intellichlor IC-40
    Awesome Tiki Bar!!!!!

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    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
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    12,082

    Re: Help with Fas-dpd test results

    After adding powder and FAS-DPD reagent getting it to clear, let it sit for 10 seconds or so, then add more drops to get it to clear, then wait 10 seconds or so, etc. At some point, it will mostly stay clear. Then, add the R-0003 reagent and see if it turns pink and how many drops it takes to get it to clear. If it's a lot of drops after R-0003 to get it clear, then the Combined Chlorine (CC) level is very high and was causing "bleed through" into the main Free Chlorine (FC) portion of the test. This is a known phenomenon and there's not much you can do about it if the CC is very high, but then again you need to deal with the CC in that case anyway.

    You could also just keep the bottle in one hand and the tube that you gently swirl in the other hand so that it doesn't take as long between drops in the FC test. You could also use a 10 ml sample so that each drop represents 0.5 ppm so that the test will go faster.

    Richard
    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"

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    frustratedpoolmom's Avatar
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    May 2007
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    Re: Help with Fas-dpd test results

    I felt your post was worthy of it's own topic, so I split the topic.

    Question for you, when you began the process of clearing things up, what was the CYA level? Had it fallen to 0?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Help with Fas-dpd test results

    Yes, this was just after the pool had been opened and they had not addes any CYA yet.
    17,000 gallon IG Humpback Kidney
    333k Sta-Rite Max-e-therm Heater
    Sta-Rite Modular Filter
    Intellichlor IC-40
    Awesome Tiki Bar!!!!!

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    frustratedpoolmom's Avatar
    Join Date
    May 2007
    Location
    SWSuburban Chicago, IL
    Posts
    11,965

    Re: Help with Fas-dpd test results

    When you say opened... do you mean for the season, that it had been winterized? Was CYA present when they closed the pool for winter?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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