Help! My arms aren't growing

[BigBossMan]

Weird, because I have read that hack squats are pretty hard on the knees, and that squats are perfectly fine as long as you have good form. I would love to do hack squats, when I go home this summer and lift at the 24 hour fitness, I'll be doing leg press and hack squats after squats.

 

[Lee]

i was told hack were easier on the knees, and i havent had any problems yet