I was worried about that with my 150, nowhere near as big as a 300, but I looked at premade stands for 150g tanks and didnt see any 2x4's or anything, just 3/4" sheets holding it up. I used 4x4's anyways to support the corners and middle of the stand, and a couple 2x4's also, and have no worries at all, other than having to move it....cs