Node stems are turning red

Hello all, I currently have a female(possibly 2) about 1.5 feet away from a 150 watt hps light. The plants are 2 weeks into flower and are at day 56 in the growth cycle. What is causing the redness in the branches? Is it a nitrogen deficiency? Any help or advice would be much appreciated. Also, can someone tell me if the other plant is a female? It appears to be flowering the way a female would, but a noob like myself wouldn't know the difference. Thanks

Red stems is indicative of cooler night time temps, in fact those who call themselves educated in these matters argue that it is anthocyanin or just food coloring 'red' those who smoke canna (me) just know that if you have a cool grow room at night the plant can't move its nutes around, too cold, and the anthocyanin, is actual visible potassium(K), .. plants got to make a choice of (N) (P) or (K) and leaves (K) behind, note too that this red ning of the plant is now highly prolific with almost all new strains, keep you temps up at high at lights off, but don't be surprised if it don't go away easy like

if your on 12 12 for a week or more up to 2 or 3 weeks sometimes.youll begin to see hairs or balls if your still on veg cycle,then you wont be able to tell,theres alot of information on red stems,i have some,and i also have low temps at night,50-60 lights off,75-85 lights on im doing it that way to simulate real weather,toward the 4th or 5th week i plan on warming it up for couple weeks,then going back to the low temps,your plants look about like mine did few weeks ago,and i have noticed that some of the red stems have went away,so hopefully youll be fine

Thanks for the advice. Im not adding any nutrients currently, as this is my first grow, but i do have then. Would you recommend using them? Also, i have a pretty powerful oscillating fan about 5 feet from the plants. Is this posssibly affecting it?