Dry and curling, when flush?

your temps are too high, thats why you get leaf tacoing, you have salt build up, in soil it becomes obvious after overdrying pot, always water with run off, water in parts and intervals. lets say you put 3 liters in one watering session, so divide it into 4-5 parts and water every 5-10 min for better saturation. it will take some time, but plants will love it. collect all run off, dont let plant to stand in it. raise your lights and increase air exchange for reducing temps.