OTO Testing Question

[BigDave]

... first drop turns orange, the 2nd drop goes brown, (about the color of fine Kentucky Bourbon) then the color gets lighter with each additional drop. When I'm finished it looks like the FC is about 4. Should I be seeing this?

No you should not. Don't look at the OTO test until you have all five drops in the the sample. Well, look at it so you can aim but don't read it until all five drops are in.

[Watermom]

OTO is not bleached out even at high chlorine levels. DPD (pink color matching) is. That is probably what Carl was thinking of.