I'm currently working to get my TA down to 80 to fight a gradual creep in PH. As I get closer to my target number I'm trying to be as accurate as possible with my measurements.
Initially as I add drops of R0009 to the solution I'll see a slight tinge of red which disappears after mixing. As I approach the end of the test there's a point where I'll add a drop which turns the majority if not all of the solution light red. A final drop causes the solution to go to dark red and subsequent drops do not seem to have any significant impact on coloration.
Should I stop counting on the last drop I described (dark red - when the drops have no further effect) or the next-to-the last drop (light red - major color change)?