+ Copper kills algae and causes stains.
+ Low pH dissolves it out of Nature2 cartridges, but if you want to know more use the PF customs search (link in my sig) to search for "Nature2"
+ Chemistry classes would help less than you think -- my older son is graduating honors with a Biology degree and Chem minor -- he LOVED organic chemistry -- and my younger son completed honors high school chem with a 97 on his final, and when I ask them stuff, they are both constantly saying stuff like, "Dad, we didn't study THAT!"