Your plants are going to be fine. Much better pictures! I still am convinced that it is an environmental problem coupled with nutrient overdose. Definitely raise the lights as suggested. Also, how much air do you have blowing right on the leaves? Is the air straight out of the air...
Heres how i have found it works in organic soil. Feeding when temps are 75-77 f degrees and humidity between 45-60 is best. When temps start to get above 80 and relative humidity around and below 40 plants will start to use primarily water. If you continue to fert in those conditions you will...
Not experienced with hydro, but i would definitely get that bubble disc, and the air pump plugged back in ASAP. As for the landlord situation, is there no space that he definitely wont be going in to that you can lock up, or be sure to keep him out of? He shouldnt need access to your entire pad...