Wow, just wow. After reading the whole thread I have to break my streak of lurking on RC to congratulate you on an amazing result. Your ability to take on board both compliments and criticism and willingness to make changes, sometimes massive and time consuming, is a credit to you. I look forward to seeing how you and your team further develop this tank and its inhabitants, and can only hope one day I can build one as well planned and thought out.
I think this is almost a perfect definition of your concept of "best practice". Good practice would be to ask the store clerk what the water parameters were, but best practice is to test yourself. In this case it is almost certain the difference between good and best was the difference between life and death for your new arrivals. It also shows best doesn't have to be more expensive, in the long run it may actually save time and money, it just needs a little thought and care.
-Kid