Stumped! have reached my skill level,please help before it gets worse.

All plants are in potting soil, peat moss, perlite, vermiculite,plants are 4 weeks into flowering, they all seem to be healthy but i am having a hard time narrowing down my leaf problem. For most of the plants life i have been nervous to over nute. Could my plants be wanting more nutrition? I just bought terra flora 2-2-4-.. i have been feeding 15ml per gallon. One feeding so far, I was using lite lite miracle grow before, but very very little.. I have read as many post i can..Some say lack of food, some say too much, I also have purple stems on one of the plants..MY temp is between 72-80, i use cfls, i have had pretty good success but i cant fix this problem on my own, I just joined this site and i cant close the page i love it! thanks to anyone who can help/

looks like either a light burn or you spilled nutes on the leaves and they burnt. as I can only see it on the one part of your plant, and the burns are side by side... you know what I mean... like the leaves look _green-burnt and the the other leaf is burnt-green... like something in the middle of the two is where the damage happened... as opposed to a burn on opposite sides of the leaves...