You've gotten really good advice. I'll just add you should be using a red heat lamp/bulb, if not already. Seems to calm the chicks.
If you haven't started snacks, try giving them some grit and then put in clumps of sod for them to peck at. I started that at 3 wks old and they loved it. The first day, they didn't do much but the next day, the grass was gone by the time I got home from work.
Different roosts or things for them to climb on. I had a flat topped rock in mine that they loved, apple tree branch roost, and a doweled dish rack I had leaning on its side that some loved to climb up. I would sprinkle a little scratch twice a day for them to scratch. That kept them from pecking each other because they had something to scratch.
I had ten standard sized chicks in a 169 gal stock tank with red heat lamps and NEVER had any pecking or aggression.
Good luck with your quickly growing little ones.