yellowing leaves 5 weeks into flowering

I started a 16 oz cup grow and im a little over 5 weeks flowering and now all my fan leaves are starting to yellow. some of the bottom leaves already died off. There is barley any amber hairs but the bud has started swelling. Im thinking phosphorus but im a newb and need a experienced opinion.


-bagseed 5 weeks into flowering
-grow cab is 2.5'x2.5'
-3x105w 5500k cfl's
-3x100w 2700k cfl's
-temperature runs 75-80 F
-foxfarm ocean forest soil
-beastie bloomz nutes every other watering (i water every 2 or 3 days)
-ph around 6

Attachment 284587
This helped me cure some problems I had.

thanks for the reply. I got it sorted out now. i switched to beastie bloomz too early and needed more nitrogen. I mixed 1/4 tsp open seasame with 1/4 tsp beastie blooms and the yellowing stopped.