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Thread: DPD (no FAS): the longer it sits the pinker it gets

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    DPD (no FAS): the longer it sits the pinker it gets

    After putting in the 5th drop of R-0002 and shaking, the color barely registers on the border of 0.5-1 / 1-2. But, if I let it sit five minutes or so it darkens and get to the 2-4 / 3-6 range. Which is true - the immediate color or the later color? OTO always seems to validate the 2-4 / 3-6 range.
    24000 gallon in-ground | 500 gallon spill-over spa | SWCG T-15 cell | PS-8 control panel | Solar panel heating | Propane heater | Jacuzzi TM 31 sand filter | Jacuzzi 2HP 240V pumps (one each for filter and spa jets) | Jacuzzi TM 31 sand filter | Auto-leveler |

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    Re: DPD (no FAS): the longer it sits the pinker it gets

    What are you getting for CC? After adding the R-0002 and reading the level, then you add R-0003 to see how much darker it gets to determine the CC (combined chlorine).

    You're only reading FC with what you're doing. The OTO reads FC (free chlorine) + CC, which equals TC (Total chlorine). You probably have high combined chlorine or it's a result of MPS.

    Are you using MPS (non-chlorine shock)?

    You really need to get an FAS-DPD test kit.

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    frogabog's Avatar
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    Re: DPD (no FAS): the longer it sits the pinker it gets

    Do you by chance have a Leslie's kit? Is it new?

    Those reagents are what was used in the Taylor K-2005. They work, but the DPD test is so much better. No guess work, and all you do is count drops. Color matching isn't easy for me although I did use that test all of last year and into this year with success.

    You can always order a DPD kit and then you'd have what you need. The nice thing about the R-0001 and R-0002 reagents is that they are reds. I like reds better than the yellow of the OTO but neither tests above 5ppm. DPD is the way to go for sure, unless I am sure the pool is low I use the DPD.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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    Re: DPD (no FAS): the longer it sits the pinker it gets

    There is a bleed-through of CC into the FC test for DPD if you wait too long -- more than a couple of minutes or so. Nevertheless, FAS-DPD seems to be more accurate than DPD regardless, at least when using a visual comparator for DPD.
    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
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    frogabog's Avatar
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    Re: DPD (no FAS): the longer it sits the pinker it gets

    If I let mine sit for a while, I do see a tinge of pink. Not so much though, just a tinge.

    On the other hand, I let the sample sit for about 1 minute at dad's the other day and it turned hot flaming pink.

    I took that to mean he was on the ragged edge of ok. Very suspect IMO.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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    Re: DPD (no FAS): the longer it sits the pinker it gets

    Thanks All,

    Yes, I use Leslie's basic DPD kit (R-0001, R-0002, R-0014) for FC testing and the HTH 6-way kit for TC and then using grade school algebra I can determine CC. Someday I will get a "proper" kit but I think for now it would only get me FAS and a rather useless acid demand test over the kits have now. Also, I'd rather use that money towards an upcoming RO service to remove excess calcium that was detected by my inferior kit. Enough about kits and sarcasm.

    So, now my pink and yellow levels are almost equal upon initial reading. When at first I was getting almost no pink, I worried and ran off to Costco for a bunch of bleach. I avoided setting the SWG to "super chlorinate" because I didn't want to stress the device. I normally run it somewhere between 45 and 65 percent. I never used the bleach and now without explanation my levels are almost equal and in fact a little high.

    Questions:
    Does a SWG system catch itself up by constantly producing FC such that CC just withers away over time? Ca CC be destroyed only by shocking?

    TC 5
    FC 5
    pH 7.5
    CYA 70
    TA 80
    24000 gallon in-ground | 500 gallon spill-over spa | SWCG T-15 cell | PS-8 control panel | Solar panel heating | Propane heater | Jacuzzi TM 31 sand filter | Jacuzzi 2HP 240V pumps (one each for filter and spa jets) | Jacuzzi TM 31 sand filter | Auto-leveler |

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    Mod Squad Bama Rambler's Avatar
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    Re: DPD (no FAS): the longer it sits the pinker it gets

    CC actually gets created when the FC is getting used up. In an outdoor pool CC gets destroyed by UV from sunlight. If you let the swcg run and there's not a lot going on in the pool it can "catch up" over time. That doesn't normally happen because once algae gets started it reporduces exponentially and the chlorine production can't keep up with it.
    Dave J. TFP Moderator
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    frogabog's Avatar
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    Re: DPD (no FAS): the longer it sits the pinker it gets

    Fathom,

    If you added the FAS-DPD kit from www.tftestkits.net it would complete your current kits. The kit only has the FAS-DPD tools/reagents, no extra demand tests or anything else that you don't need.

    You will get a cylinder, a scoop, R-0870 DPD Powder, R-0871 Titrating Reagent, and R-0003 reagent. http://tftestkits.net/FAS-DPD-Chlorine- ... t-p47.html
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

  9. Back To Top    #9

    Re: DPD (no FAS): the longer it sits the pinker it gets

    Hey Frogger,

    That's exactly what I needed to know. I'll probably go ahead and order the FAS kit and a magnetic stirrer. Thanks for the tip.
    24000 gallon in-ground | 500 gallon spill-over spa | SWCG T-15 cell | PS-8 control panel | Solar panel heating | Propane heater | Jacuzzi TM 31 sand filter | Jacuzzi 2HP 240V pumps (one each for filter and spa jets) | Jacuzzi TM 31 sand filter | Auto-leveler |

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