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Mg overfeed

Hello mate, looking your plants this porblem seems to be linked to immobile nutrient, like Mn Zn Fe. Normally all problems that come from immobile nutrients start showing in the top of the plants. Try to look some guide that teach how to recognize which of immobile element is boring you now. Good luck and happy journey!

Nitrogen toxicity is what it is, it is not a deficiency of any sort...............basically over fed/nutrient burning.

Also magnesium.

I also think its potassium related.

Looks like a potassium deficiency or lock out.

Probably a root problem what do your roots look like are you useing anything like hydrogaurd. Growing hydro is hard don't get down on yourself. If the plant dies die I suggest tring soil or coco or something similar next time