Reeeeeally looking forward to seeing the finished tank with fish. (I love that background. Very cool.)
Where did you get the styrofoam at? I'm having trouble finding thick enough pieces.
I used regular sheets of white styrofoam from Home Depot. They're not very thick - about 1/4" - 1/2" each. Home Depot also carries pink insulation foam that is much thicker and might be better for your purpose.