I just want to say one thing so we're all on the same page. Many knowledgeable people have assured me that a low-to-medium light low tech tank runs fine on fish food -> fish poop for P and K, Nitrogen from the dissolved compounds in the water, plus trace elements (Comprehensive) as directed. With that in place, any problems must be something else, or the light is wrong, etc.
Unfortunately, although Aquariology sits on some science, we don't have the equipment or the training to use it. So, it becomes an art. I am coming to the conclusion that for myself, a familiarity with what to do with a planted aquarium comes through personal experience, and there's no hurrying it along any faster. It *is* useful to find out what other people are saying about and doing with their balanced Planted Aquariums so it may be used when you get there.