Great build Catherine!  Most of us only dream of a tank like this. 
 
Anyways, I've been prepping for a large build (although not quite the size of yours) and after reading as much as I could, it seems to me that an HRV has benefits above and beyond that of the humidex.  While the Humidex seems aimed at the humidity issue, the HRV is more of a total home solution that handles the humidity too.  It also seems to be the more accepted technology out there from a builders perspective. 
 
Quotes will obviously be the biggest deciding factor but I thought I would throw my 2 cents in. 
		
	
		
		
		
		
			
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				Mark...
  
290g Peninsula Display, 425g total volume.  Setup Jan 2013.
			  
		
		
		
		
	
		
		
	
	
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