Well said. If they're pissed enough to consider takin a bat to your babies you might wanna rethink growing. When they get to flowering things are gonna get stinky.
Looks like nute burn indeed. Try flushing with clean water for a week then start over with 1/4 strenght nutes working up to full strength. The lights are too high that's why it's stretching. Cover those holes!!! You don't want light in your reservoir it'll cause all kinds of problems. pH should...