need feedback?

I've been growing this strain awhile, they used to be good from start to finish. 5 weeks veg 9 weeks bud but lately they have been changing color in the leaves about 3 weeks in bud and i cant figure out why. I have a couple of good ones you can see but the rest not so good. ph is 5.6, temp is 75-80, humidity 30-50% and ive tried keeping the food low 1000-1200ppm and on the next batch high 1400-1700. Still they do the same thing everytime. The clones i get are from a old strain, mabey its dead? i dont know what do you think?