I've been doing alot of squats for the past year or so. Thorwing 10 lbs. or so on every 1-2 weeks. I like to do them with very strict form and go past parallel, almost as far down as I can go. My question is, is there a weight that when I reach I should consider not going down that far. I'm just worried about having a knee blow out with a whole lot of weight on my back. 