What size old, what size new, how old is the sand, and will you be adding more (new) sand to it? 
I added all the sand from a 75g into a 155g, no issues. It can go terribly wrong though, so fill in the questions above and that will give a clearer picture of wat you want to do. 
		
	
		
		
		
		
			
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				Brad
			 
		
		
		
		
	
		
		
	
	
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