Its been a decade since my last grow. Forgot I needed to do a flush once a month for my flood and drain in coco. There must've been nutrient build up near the top of the medium. Here they are. Tell me what you guys think.
What are you growing in, and what have you been feeding? Doesn't seem to be a nutrient burn, but rather she's not getting her share of potassium. Not all burning at the edges and tips mean over fertilized.
Just be aware that when growing on coco the return water isn’t necessarily going to contain an even mix of all nutrients required for next feeding and you may get really low pH or really high pH readings depending upon how the plants are extracting what they need.
Coco in itself needs high K just to sustain its CEC capacity.
Personally I always throw my coco return water onto my garden outside rather than reuse it on my girls.