rhodes68answered grow question 5 years ago I do not see any mention in your diary of the coco coir itself.
How was it prepared?
Was it buffered?
90% of problems in coco are caused during the prep for the coir itself.
Ill preped coco will strip the CA and MG right out of your plants as a worst case, out of your soil commonly.
A foliar spray would be called for if thats your issue.
Long term you will be adding cal-mag through the grow
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