split the drain
			 
			 
			
		
		
		
		i would seriously consider spliting the overflow drain into two. if the overflow gets blocked past your "T" you're screwed.... at least if they are plumbed individually you have redundancy. i have had no issues with my DIY system which is like yours but individually plumbed. 
		
	
		
		
		
		
		
	
		
		
	
	
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