Definitely not light burn, but if you are giving more intense light than previously, you need to feed slightly more... although most people feed plenty and need to calculate ppms to be certain about that sort of stuff.
check out my spreadsheet linked in my profile comments. download it, no macros exist, only formulas in cells. adds upto 10 products together from % of label (usa standards). if %w/w need to fill in last to input columns too.