Curling downwards on your top growth points out nitrogen excess, 1EC is too much for this size.
I bet this caused some ph fluctuations around the root zone. Give it a nice flush with mild strength nutrients and go on from there.
Hope this helps ! best of luck
Check your runoff waters ph and ec levels. Likely lockout happening. Just need to figure out if it's ph or ec. I don't know the age of your plants so I can't say what levels you should be at. If you need help with that, you can contact me directly.