CC test

[phillman5]

I am just starting out reading TFP, my concern it the FAS-DPD test for CC. I think of getting the TF100 kit. Here are the directions I found elsewhere on TFP:
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FAS/DPD Chlorine Test​

separately measures FC/CC.

1. Rinse and fill sample tube to 10ml mark.
2. Use teeny blue scooper (hold the flat end) to put one heaping scoop R-0870 powder into sample, swirl to mix. (OK if not all dissolves.) Sample should turn pink. If it "flashes" pink then the pink disappears, add more R-0870. If there's never a hint of pink at all, skip step 3; FC=0.
3. Add R-0871 one drop at a time, swirling the sample continuously, 1-2 sec between drops. Stop when sample turns colorless. Multiply #drops by 0.5 to get FC. (If it turns pink again after a few seconds, don't worry about it.)
4. Add 5 drops R-0003, swirl to mix. If it remains colorless, CC=0. If it turns pink, again add drops of R-0871 (swirling continuously) until it turns colorless. Multiply drops by 0.5 to get CC.

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MY question concerns that in parenthesis at the end of step 3. If it turns pink again (end of step 3), how you suppose to continue to step 4, because its now already pink? I mean step 4 sounds like it assumes sample does NOT turn pink at the end of step 3.
Is there another more accurate CC test? I mean you are suppose to SLAM if CC>.5, and this means just one drop in step 4.

 

[zz28zz]

That's the "course" method in my Taylor K2006C kit (0.5ppm resolution). There's another test that uses 25ml of water and 2 scoops of R-0870. This "fine" test method gives 0.2ppm resolution. Haven't seen a TF100 kit but assume they are very similar.

I had the same concern abt turning pink again but found that adding 1 drop of R-0871 cleared it up. So using the "fine" method, I figure I'm somewhere between 0 and 0.2ppm of CC. Probably closer to zero CC. Other option is be ready to do the CC portion immediately after FC part; i.e. before it starts turning slightly pink.

 

[Newdude]

MY question concerns that in parenthesis at the end of step 3. If it turns pink again (end of step 3), how you suppose to continue to step 4,

I know what they're saying, but it needs to be said better.

When you're done with the test, whether or not you tested for CCs, the solution will often turn pink again on its own if you don't immediately dump it.

That event does not count for the test and it fools many people who then start adding drops again.

Do you have a link to where you found the above ?

 

[Donldson]

It takes almost a minute for the test to start turning pink again.

I don't believe we've encountered a situation where someone waited so long between the FC and CC test for this to be a problem. Typically we get someone who did the test, sat the sample down to record the results, started doing another test, and then noticed the sample had reverted to pink and were concerned. That is why there is a reminder of this.

 

[PoolStored]

Drop until clear.
Do not pause when adding the r-0003. Add within a second or two of clear.
That is correct, CC = .5 with one drop to clear.

 

[Bperry]

I mean you are suppose to SLAM if CC>.5, and this means just one drop in step 4.

This is not accurate. You keep a SLAM going if CC is 1.0 or above but simply having 1.0CC is not a sole indicator to start a SLAM. Failing an overnight chlorone loss test would be a reason to start a SLAM, but not slightly elevated CC level all by itself.