Been using this method 4-5 years. Fresh reagents from TFT this spring. When testing for FC, the color is initially deep pink. Adding R-0871 eventually turns it to pale purple; it has not gone clear in weeks. I'm guessing at the FC level, around 2.5 and adding bleach accordingly to get to 4.0. When I test for CC, I also cannot ever get the water in the test tube to go clear. I notice the test cylinder has become stained light purple. And, to my eye, the R-0870 powder is much darker than I remember in the past. I'm careful with the little spoon, and do not get it wet. My pool water is clear, no problem, but I think I'm using more bleach this year than last, even after pushing the CYA up to 40.
I am concerned about the R-0870 reagent. Any ideas? Thanks.