Trace CC

[azimmer1]

Hi
I used to be a regular contributor to this forum (The old software 3 years ago) and I have been away for a while. I have a question for the pros
My pool has been clear for years with FC levels around 4-6, CYA 20-40,
(My pool is covered when not in use so I don't need much CYA) pH is 7.4
TA is just fine.

I always get a trace of CC when adding the KI drops. Typically it clears with one or maybe 2 drops of DPD/FAS so I only have 0.5ppm of CC.
The CC is never zero, always a trace. It doesn't matter if I shock to FC of 15 ppm.

Do you think I always have a mild contaminant creating the CC or is this just false positive.

Well Janet, CarlD what do you think....Are you both still on this forum

[KurtV]

I think it might be your testing procedure. Make sure you're adding enough drops of the R-0871 reagent. Per Taylor's website, "When you think you’ve reached the endpoint, add one more drop of titrant to be certain the color change is permanent. If the color remains unchanged, do not count this last drop." I've found that the Taylor FAS-DPD test will often incorrectly show 0.2 or 0.5 ppm (depending on the sample size) combined chlorine unless you follow that procedure

[azimmer1]

I will give that a try, but my sample is crystal clear before I add the potassium iodine.

[aylad]

Hi
I used to be a regular contributor to this forum (The old software 3 years ago) and I have been away for a while.
I always get a trace of CC when adding the KI drops. Typically it clears with one or maybe 2 drops of DPD/FAS so I only have 0.5ppm of CC.
The CC is never zero, always a trace. It doesn't matter if I shock to FC of 15 ppm.

Do you think I always have a mild contaminant creating the CC or is this just false positive.

Well Janet, CarlD what do you think....Are you both still on this forum

Hi, and welcome back!
Carl and I are still here, as are Poconos and Watermom.

You aren't the first person I've seen on this forum who has experienced the eternal .5 CC, and there have been stretches of time when I've had that happen in my own pool, as well. If it's remaining after shocking, and you have clear water with no sign of algae, I would consider it a false positive and not worry about it.

Good to see you back on the forum!

Janet