Was thinking about #STT & the many variables associated with it. Below are very rudimentary formulas that I was contemplating.
STT= Established major reference points \ divided by \ % of new changes
Would need several "gold standard" reference points to even begin comparisons. Here is a sample:
1. Calculated surface area
2. Total time without any changes to aquarium
3. Live plant stocking factors
4. Type of substrate
5. Others
Also, maybe an "additive" test with ammonia itself, so see when the beneficial bacteria is actually starting to become stressed, etc. This could be another reference point. By determining how much ammonia would be required to see a small ammonia/nitrite increase, could indicate overall % of beneficial bacteria for a specific tank.
I.E. STT= 10 gallon aquarium \divided by\ Ammonia added in (ml)
Just some ideas that came to mind this morning......