I recently received my FAS/DPD stuff from Dave at TF test kits. Makes me never want to go back to OTO testing for chlorine
The procedure I've been following is-
1- 10ml sample of pool water.
2- Add DPD powder until the sample turns pink.
3- Add drops of R-0871 until sample turns clear. Divide drops by 2 (each drop is .5 ppm of FC) to get FC.
4- Add 5 drops of DPD #3. If sample turns pink, CC is present.
5- Add drops of R-0871 until sample turns clear. Each drop is .5 ppm of CC.
So far so good
What I'm wondering is do I have to test for FC first, or if all I want to know is if CC is present can I simply take the 10ml sample, add the 5 drops of DPD #3 and then add R-0871 to measure CC?