PhD Application - if/where to explain reasons for poor GPA 10 years ago
Explain poor grades in your statement of purpose/essay, which is where evaluators are going to look for it. These statements can be up to a couple of pages long, so you can (and should) spare a paragraph (or two, if necessary) to the topic. The explanation must be detailed enough to give a reader a picture of what happened, and the confidence that the underlying problems have since been addressed.