im not experinced enough to know. but have you looked at these COMPLETE GUIDE TO SICK PLANTS- READ BEFORE NEW POST | Stoner Forums https://www.icmag.com/ic/showthread.php?t=11688 maybe zinc lock out from high phosphorus? "Too much Phosphorus levels affect plant growth by suppressing the uptake of: Iron, potassium and Zinc, potentially causing deficiency symptoms of these nutrients to occur def in plants. A Zinc deficiency is most common under excessive phosphorus conditions"