Veins turning light green on lower leaves

consuming and transfering energy more, nothing special i would say, that litle in most recent week, photo number 3 could be magnesium isuus, but why you only know . short option list in my mind : bad ph excess of nitrogen bad watering regime simple. Action by me : 2 plain water cycles, on second adding 0.25 ml/l of cal mag , if after two she is perky, return to that weeks by schedule nutrition program, just first feed do 50% weaker than recommended or you would normally give. Summary compared to 5 days ago : the one you worry, very nice, maybe a bit hungry, if ph is definitely good - no changes needed, all goes well. tall in the corner should have a bit bigger PK , than others, she is hungry on that part, but watch PH with her, she was worst, no i would say she is ok. other looks perky too, just sort that small one with possible magnesium issue and your grow is back to wonderful path ! Happy Growing !