Hey Steve,
I attended your talk as well. I thought that you did a decent job and your main points were articulated well. I do have a lot of constructive criticism about you experimental design and flaws of your data collection. However, the lecture was delivered well.
I would have liked to see more comparisons of the measures of pH, Ca, Alk, Mg, etc with the different additives. Observational studies, although important, do not add much solid science. Pick a hypothesis and try to prove or disprove it. If you just to collect observational data, than try to determine what measurable parameters can change! Keep up the good work, from little acorns..........