Drop Based Borate Test Kit.

[chem geek]

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).

[waterbear]

Exactly! The problem is that you do not really know the acutal borate reading. You can get repeatable results as long as you stop at the same transition point but where is the PROPER place to stop to get an accurate boron reading? The strips might not have the same precision but the resutls are more accurate in terms of boron levels, IMHO.

[chem geek]

The point I was trying to make was that it doesn't matter exactly which point you stop for the transition so long as you stop in the same place in both parts of the test where that transition is seen. I got the same borate result (same number of drops in the second part of the test) regardless of the transition point I used (just barely blue vs. a more solid blue, for example) so long as I went to the same point in both parts of the test. My five tests even at different transition points all gave me the same borate result within one drop (actually, 4 of the 5 were exactly the same number of drops). Basically, if you go "too far" in the first part of the test, then it is exactly compensated in the second part of the test if you go to the same visible point since what you are trying to measure is the delta that happens after you add the mannitol. The exact transition point from which you start in the first part of the test and end in the second part of the test isn't important (since even a hint of blue is beyond that needed to measure the borates properly).

[waterbear]

so long as I went to the same point in both parts of the test. .

and it is a subjective color that you are trying to achieve by memory. I never said that this test was bad, just that it was difficult to do properly and can be error prone and is time consuming compared to the LaMotte strips..