So I come home today and read a post where somebody tested the TA and pH of rainwater - It rained here about 3/4" today, so I figure seems like a good idea, I'll do the same. I expect 0 TA, but who knows? Anyway, I empty my rain gauge into a 50ml graduated cylinder and pour out the excess 'til my cylinder has 25ml, and go in to test the TA. I pour it into the test cylinder of my tf100, and it reads 29ml.
OK, thinking maybe I screwed up, I pour my sample back into my graduated cylinder - 25ml. Back into the test cylinder - 29ml. Hmmm. What does this mean for my TA test, or my CH test?
Now, I fill my graduated cylinder to the 10ml mark, then fill my "chlorine only" test cylinder - 13ml. So, what does this mean for my FC and CC tests?
I trust my graduated cylinder. Come to find out, my FC may have been a little low because I've unknowingly been testing with not enough sample.
Has anybody calibrated their test cylinder to a known standard? Hadn't I come across some mustard algae recently - I would have thought that this finding is relatively meaningless - but maybe it's not.