Quote Originally Posted by chem geek View Post
Blue to yellow in the TA test is normal when the FC is high. This is described in the Taylor interferences description here. It's still a valid test -- the colors will just be different. As an alternative, you can add more thiosulfate (R-0007) when you know the chlorine is high -- around 2 drops for every 10 ppm FC, maybe a little more.
Nice! Yes, when you run the T/A test you are supposed to start with 2 drops of R-0007--the chlorine neutralizer. But it's nice to know that if your FC is between 10 and 20, you need two more drops. Thanks, Richard!