I finally got around to transferring my water measurements onto a spreadsheet. Bascially, when you have time to do this, you know your system has stabilized!
For those that are interested, below are my pH, amonia, and nitrate measurements. Unfortunately, they only go back about two weeks. There were some pretty major disruptions to my system in the time before then (gravel switch and then the tank repair job) so who knows if even those measurements would have been very meaningful. I know they would have made for some interesting charts, as my pH got up to 8.6 several times when I had the old gravel, and my nitrates ventured into 160ppm several times which led me to do some water changes.
I think these graphs capture the "tail" end of the maturation of my system, as pH, amonia, and nitrate all appear to abruptly stabilize. I have not added any phosphoric acid since last Saturday (5 days ago), so I think we're in for some smooth sailing.
Very bad news on my fingerlings. Last weekend, I pulled the floating basket up out of the water to check on them and found several dead fingerlings. This led me to semi "panic" and I decided to give them a salt bath. I had seen recommendations on giving finegrlings a salt bath once a week, but I do not know how much salt is the right amount. If I measured correcty, I gave them a 10% salt bath for one hour. I then put them in the sump, not back in the floating basket, which seemed a bit constraining.
Every day since then, I or my caretaker has pulled anywhere from 15-30 dead fingerlings off the pump filters in the sump. I do not know what is killing them, but I'm pretty sure they will all be goners at this point. Whatever it is, it is not affecting my big fish (so far, knock on wood).
I definitely need to identify the source of the problem so as to not repeat it. In the meantime, time to find more fingerlings or play some romantic music for my big fish to propogate again.