Yea, easy one. but dont take what I said to heart with out your info on fret strength etc. But it could be a over aboundance of micro nuts, generally leaf tips will curl sharp up, or sharp down depending on the micro nut responsible. Also a suddent pH flux is also responsible for the tip curl up or down. If u did everything to script than I would have to agree with everyone else that plants hate FF stuff. Im a GH 3part guy and I support the new nutrent manufacture on the block. Innovating plant products. Only manufacture that takes new research and recognizes it in there feed. Adance does, but this is there main scientist that left them
Cheaper prices and better water soluble products. Anyways good luck with your prob.