+1 strain
My friend, I really believe your plants are lacking Calcium and Magnesium. You can try adding those to your feeding schedule if you haven't or even better - flush your plants under the shower to get rid of all the brown water with built up stuff in it than screw up your PH.
Another reason for curling the leaves upwards is heat stress - pull your lamp a little higher (test with your hand at the top of the canopy - If it is too hot for you - it is too hot for them, too)
Besides that - OMG!! Your set up, plants and everything are excellent! I love how big they are :)))
like
