purpleing leaves!! whats up with that

hi i have noticed that some of my leaves towards the top of my plants are starting to get a purplish color tint to them. i have read up a little but couldnt find anything on it. any suggestions will help. just started doing this like last night it seems like. unless i just haven't noticed it until mow. PLEASE HELP!

well, to start with, what strain do you have? Then, your room temps would help.

r u in flowering? what is the temp? I know that my box's temp when lights are off is approx. 62 during fall/winter months and that causes my upper leaves and buds to purplize. of course the purple is a good thing when and if its time to sell

the downfall is that cool temps can slow growth

leafs turn purple when they lack nitrogen...if its not the norm for the strain.

ok room temp in day time is about 81 degrees and night its about 76 ish. strain is unknown but the stuff i got it from looked like a sour diesel and smelt like skunk. still vegging

what are u feeding her?..and whats the N-P-K?.. are u checking ur PH?..are u in hydro or soil?

oh and humidity is like 37 to 40 percent

in soil and using a miracle grow supplement which is 24 8 16. i also have a blood meal supplement thats like 12 0 0 or something. i blend that in the soil and use water for two feedings then the miracle grow solution then water 2 times the miracle grow solution. i dont want my plants to get addicted the solution so i do a 2 to 1 feeding. I have a fan blowing on it all day but not at night because i want my plants energy to go towards making leaves and buds not stronger stems. they will be strong enough. light cycle right now is 16/8.