timing of testing for FC and CC

[bkfamily1]

I have read a few threads about the time it takes for the reactions to occur when testing for FC and CC with the TF100 and similar kits. And I have observed the return of the pink color given a bit of time after the color change is complete. I wanted to be sure I understood the most proper way to test. As I currently understand, you need to complete the FC test in a minute or less. And for the CC test, you keep waiting for the pink to return until the color change holds for a minute., i.e. add drops until it is clear, wait a minute, if the pink returns, add more drops and wait again, and keep doing that until the pink does not return. Is that correct?

 

[Patrick_B]

I'm not sure where you read that, but no. Once the FC test is done, you immediately add the R0003 and see if it turns pink again. If it it does, you titrate again until it's clear and count the results as on the first round to get a new (CC) number. Don't wait around between, or after tests to see if pink returns, but do make sure you are done with the FC before proceeding to CC. Begin, and complete both tests, without delays, and you are done.

 

[bkfamily1]

I thought I was reading about the speed of some of the reactions for the testing of the CC - but I have read so much over the last few weeks that it is starting to blur together

Thanks

 

[pooldv]

Here you go, definitive instructions.
https://www.youtube.com/user/tf100testkit?feature=results_main
TFTestkits.net

 

[chem geek]

If there is significant CC, then there can be a "bleed-through" of it into the FC test if you wait too long. Dissolved oxygen can lead to interference though usually the test kit controls the pH to minimize this. So when measuring in both tests, you don't want to wait and when you get to clear that holds even for a few seconds you are done with that part of the test. However, the CC test won't resolve some of the CC quickly especially if the water sample is cold. While monochloramine will register quickly, dichloramine can take longer (I'm not sure about chlorourea). So there is value to warming up the sample to at least room temperature and you could see in the CC test what happens after waiting for one minute but need not wait any longer than that.

Note that DPD reacts with sunlight so you don't want to do your test in the sun.