Hi there! Your plants started out very well, I think from my humble experience that you are giving too much N to your plants (dark, shiny green). It's quite common to overnute with N so no worries, less is more. I think that the leaves curling at the edges is a sign of either one of these:
- very low humidity
- very high humidity with overwatering
- root problems
Reducing the N will already give your plants some air. Good luck, we all learn!
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