If you let the culture go too long it will contain a lot of dead stuff and could potentially become contaminated with bad DOCs from the breakdown of said dead stuff. Not something you want to add in quantity to a tank full of expensive corals. That said, I'm sure a week is pretty safe, but its something to keep in mind. 
		
	
		
		
		
		
			
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				Calvin 
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Planning a 29 gallon mixed reef...
			 
		
		
		
		
	
		
		
	
	
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