Is styrofoam needed under tank if there's plywood?
 

Just finished construction of my stand for the new tank.It's going to hold a 115(36x24x30.5)and has 1/2" plywood on top,so is styrofoam still needed?Does it allow for minor leveling errors,or just a cushion?

i know its used for sound proof. As for me i used shims to level the bit i needed and used the foam for maximum quiet :D

The foam allows for any slight uneveness of the stand. It will crush slightly at any high spots ensuring the tank is supported evenly across the base. Of course you still need to make sure it is fairly flat and level, the foam can only do so much. I use a piece of 1/2" extruded foam insulation (the pink or blue stuff) under all my tanks.