OK here's an additional post that's kind of a bummer.
That middle vial is a grab from the cycling tank (diluted as normal). When compared directly with a 2 or 4 vial, it's definitely not as I had thought. It doesn't appear to differ much from 4 after all.
I had thought it was distinctly lighter than my initial tests from the tank. But I'm noticing that in the absence of a "control" this is really impossible to estimate from day to day. I would say that this potentiallyy makes my early ammonia readings, where I thought it had dropped, invalid.
pH and kH
drops are not invalid however.
Also, to increase reliability of future readings, I have made a "control solution" which is 4ppm. I will now run 2 ammonia tests each time I test the cycling tank, using both the tank water and the control. Then I should be able to compare these more accurately and properly identify if the tank is reducing ammonia.
I can also dilute my control solution as needed to control for any other lesser ppm
So, not the best news. But it did seem too good to be true.
If the tank is not reducing ammonia though -why are the pH and kH
Perhaps I added slightly more than 16ppm to begin with, and it is now slightly under? I think there is a potential error range of 1-2ppm ammonia. I think there is not going to be definite information until the tank has CLEARLY reduced at least into the 1-2ppm range.