Measuring TA with the TF-100 kit

[PhillipH]

Probably being overly technical about this, but I'm still curious. I was just measuring TA with my new TF-100 kit, and on the 8th drop, the green solution turned to what appeared to be red. Just for the heck of it, I went ahead and put in a 9th drop, and then the solution turned an obvious red. In hindsight, the previous color on the 8th drop was actually more reddish-purple, but it was an obvious change from the initial green. So my question is, did my TA measure as 80ppm or 90ppm?

Similarly, during the CH test, the solution turned bluish-purple on the 17th drop, but then turned an obvious blue on the 18th drop. 170ppm or 180ppm?

Thanks.

 

[dmanb2b]

90 and 180....your looking for the last color change, more than a specific color...once the color no longer changes you stop counting the drops....good question

 

[PaulR]

Yep, mine usually does that too. You count drops until it starts changing, and then stops changing. So really, you should have put in a 10th drop (TA) or 19th drop (CH) to make sure the color didn't change any more.
--paulr