So just to be sure, you add DPD powder to a 10 ml sample and it turns pink/red. You then add R-0871 until it turns clear which in your case takes 8 drops so 4 ppm FC. Then to that same sample you add 5 drops of R-0003 and the sample turns pink/red again. Then you add R-0871 until it turns clear which in your case takes 7 drops so 3.5 ppm CC. Do I have that right? I'm just trying to make sure that you didn't start with a new sample when you measured the CC and that you measured it using the same sample you used to measure FC (i.e. that you did the CC test following the FC test using the same sample water).