Ya, I like to keep the styrofoam about 1/4" larger than the tank on all sides.  I usually just cut the sheets into 2" strips and put that around the perimeter of the tank, and then a small patch in the center to help keep the bottom from bowing.  If the tank has trim you obviously don't need the patch in the center. 
		
	
		
		
		
		
			
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				~ Mindy 
 
SPS fanatic. 
			 
		
		
		
		
	
		
		
	
	
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