Poconolg,
Nobody seems to want to answer your question with a straight face. I honestly don't know the answer, either. Simple Green is alkaline, with a pH of about 9. This means it will neutralize acid up until the pH is neutral, at which point its cleaning properties will be compromised, so you likely won't get good results combining it with citric acid (Lemishine, lemon juice, etc.) You can try it by itself to see how well carbon is removed, but I wouldn't expect it to handle brass corrosion as well as the citric acid-based soluitions.