Your method of filtration is fine but I wouldn't use DI resin as it will get depleted faster than having run in conjuction with a membrane. 
I thought of doing a similar setup to my system running only filtration with no membrane as I like to keep some of the ions after filtering to go to my system... 
		
	
		
		
		
		
			
		
		
		
		
	
		
		
	
	
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