I don't think this will solve your troubles, but you could try using smaller amounts of carbon, and changing it out more often, like every 2-3 weeks.  Your magnesium is a tad low too - should be 1350-1400 ppm. 
 
Are there any maintenance things you do every 3 weeks or so since you're noticing the algae issues at that interval?  Not necessarily immediately before the algae issue since it could take time for the corals to react. 
		
	
		
		
		
		
			
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				~ Mindy 
 
SPS fanatic. 
			 
		
		
		
		
	
		
		
	
	
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