Have my main in one overflow, emergency in another and works okay. 
 
Running a trickle through the emergency but was also worried about going stagnate so drilled a 1/4" hole high on the standpipe, threaded in a elbow with a line going to bottom. Not sure if may a differance but my tile fish went AWOL for a month and just got fatter in the e-overflow. 
		
	
		
		
		
		
			
		
		
		
		
	
		
		
	
	
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