I'm a new diver (10 logged dives) with a newbie question. I'm going freshwater diving this weekend with a new wet suit (6.5 mil 2 peice.) I 'd like an estamation on how much extra weight I'll need to bring along. Up to this point I've only worn a 3 mill shorty, with which I only need 2lbs of weight. Any thoughts on how much more weight I'll need for the 6 mil 2 peice?