The idea that I've always struggled to understand is that excess nutrients do not cause algae. Maybe I can work on a flash animation that would explain my confusion and help others understand. I was thinking of bar graph's on the left of the animation showing concentrations of micros and macros, and then bar graph's on the right showing algae and aquatic plants growth rates. We would start with a balanced tank, where the nutrient concentration favors the growth of aquatic plants rather than algae. Then overdose with say Iron. Plant growth/momentum would increase and some other nutrient would run out. When that nutrient ran out, the plant growth would stall and algae would start to grow. Do I understand this concept correctly? Is this how it works if you overdose any of the Macros or Micros?