Sweet Skunk Hydro

are you really giving 800ppm to that little tiny gal?

Like @premiumbudsEU said this is because you have high temperature with low humidity :) Make sure you get like 24-26temperature with like 80-90%humidity( i like 90 alot ) Also, i see you are doing a 24hour light schedule, you should do 18-20hours. Sure you can do 24hours a day but you have to have a perfect climate and feeding schedule for that. Goodluck growing :)

Could be heat/humidity or wind burn( Fan should be above and/or below the canopy and not directly on the leaves ). I don't see any temp/humidity in your diary so Its hard to say. Look at the VPD chart in this link( or google VPD Chart ) and make sure your temp/humidity is not in the red. https://www.dimluxlighting.com/knowledge/blog/vapor-pressure-deficit-the-ultimate-guide-to-vpd/ Happy Growing