what many people don't get about curled leaf tips is that it is not too much nitrogen or lack of light..... Too much nitrogen it would burn the shit out of the leafs and not be green and curled. Plants that are droopy that are in dirt means it needs to be water. PH can play a role in curled leaves too, but it's not the light like many people say. Too much moisture in the medium can play a role. Heat is not really the issue in leaf curl too. Everyone talks about heat, ph, ppm, and over watered, but they forgot about HUMIDITY..... Humidity(moisture) is 80% of the reason why leaf curls.... From my experience, my deep water culture sits in 5 gallon buckets, around 900ppm, temp 75degree, ph at 5.8, humidity sits at 55..... plants looks beautiful and healthier than a mutha fucker.... two weeks down the road, everything is still the same, but humidity jumps from 75-85.... Then leafs starts to curl hard...... bought a dehumidifier and humidity stays around 55-60. Plants looks beautiful again........ CHECK YOUR HUMIDITY....Obviously its not nitrogen, light, heat, ppm, root bound, or ph.... HUMIDITY....