Glad to here your tank is doing well.  It's never fun to have to deal with the unexpected problems.  My brother-in-law has a flatworm problem right now. I recommended a sixline wrasse they should take care of it pretty fast.  I see you added some substrate since the last pics.  Looking good!! 
		
	
		
		
		
		
		
	
		
		
	
	
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