The leaves are showing signs of over watering and nitrogen toxicity to me. I also seen the over watering signs in last weeks entry on the diary as well.
I would cut back on the water and double check your nitrogen input. It should fix it in a week or two,
Given you do not list how much or what your feeding with, monitoring the EC is a good tool to help prevent overdosing the plants. It will not test how well balanced the feeding solution is, just its concentration as reflected by the conductivity in the solution.
Good Luck!
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