Yes the manufacturers recommend you use foam the whole surface of the stand, not just the edges. 3/4 inch is available at home depot, very, very cheap and lite
I have an old 225gal glass tank that im working on now. the tank sits on the bottom trim with the actual glass being off of the stand. do i cut the foam board to fit the void or do i cut the foam board to go to the outside edge of the bottom trim? thanks