I received the Piscines Apollo borates test and tried it out in my pool today. I can see what waterbear is talking about with regard to not having the same sort of "keep adding drops until there is no color change, then do not count the last drop" problem, but I tried the test going past the first transition to blue in several different amounts and basically so long as you end up at the same transition point in the first part of the test (before adding the powder) and the last part of the test, then the results are very consistent. That is, if you stop adding drops when the sample "first turns blue" as indicated in the instructions, then you get the same result as when you go past that by some fixed number of drops to get, say, a deeper blue, so long as you do the same thing in both parts of the test. It does seem to me to be repeatable to within one drop as advertised since I did the test 5 times and got the same result (within one drop) -- again, so long as I stopped at the same point in both parts of the test. The transition to blue is like most other dye tests, not completely definitive in one drop, but it does seem pretty clear within two so should be easy enough to pick one's transition point to be consistent for the second part of the test (i.e. if you go further in the first part to a darker more distinct blue, just be sure to do that later as well).