yellowing older leaves and stems turning red.

yellowing of olderleaves and stems turning red on the top half???? any1 recongnise these signs?

p.s new growth is dark green and looks healthy its only the older leaves thats effected so far!!?????

using soil, checked soil ph and its smack on-6.8 wot could this be? 2wk into flower! (p) deffiency???

Too many people on this site think because a plant has a red stem more often then not it is probebly the strain or futher down the genetic line don't worry about it if only a few leaves are going yellow and dieing off its not a problem mine are in second week and i have yellowing leaves leaves do die.The leaves lower down are the first leaves to grow and the first to die take it easy have a bong and chill,I would try to lower your ph a tadd 5.5or5.7 till yhey are more in budd if it's a 8/9 week strain bang some pot ash on in thelast 2 week.