Yea if you are 4 weeks into flower you should be giving more P than anything else. I use a 15-30-15 for bloom, and a 24-8-16 for veg..... You should be using a bloom/flowering nutrient now. And I dunno if you are or not, but you shouldn't be feeding weekly. I only use nutrients about once every 2 weeks untill the plant get's to where yours are at now. Then still no more than once every week and a half.
The dark green is from giving WAY to much N. I'd flush then feed with a half strength bloom nute.