When I was running low on reagents, I made a reorder basically to use to refill my bottles in my Taylor test kit. I ordered the 16 oz bottles of the reagents with one exception, the R-8071 reagent. For the R-8071 reagent, I had ordered the 2 oz bottle. I was pleased to find that when the 2oz bottle arrived, it had a nipple on the end and thus could be use to deliver drops instead of refilling my 0.75 oz small bottle. So I went about my normal tests using the almost empty 0.75 oz bottle sometimes, and other times using the 2oz bottle. Since I am a bit OCD, as you can easily tell from reading any of my posts, I record every test and the conditions of the test.
Well after a week it became apparent that whenever I used the 2 oz bottle, I had to add more chlorine to my pool than when I used the 0.75 oz bottle. So I did a test last night using the 2 oz bottle and the 0.75 oz bottle on the same sample of water. The 2 oz bottle reported a FC=5.5. The 0.75 oz bottle reported a FC=7. The 2 oz bottle nipple produces a larger drop than the 0.75 oz! So half the time I was using more chlorine than necessary because the manufacturer decides to change the nipple size.
So the moral of this story is that you should use and stick with the test bottles your kit came with. Of course if the drop size changes your reading that much, who is to say every bottle is made to the same spec and thus will produce the correct reading?
Ugh... being OCD makes you over-think too much. I will now go back to straightening that stack of paper....again.