For some added LED info, I just did some PAR readings in the iReef pico.  it has 6 Cree XR-E LEDs being underdriven by a 350mA dimming buckpuck that I actually have turned down a little from full power.  No optics are used, just bare emitters. PAR readings were about 170 near the top of my rock which is about 4 inches below the surface of the water and about 5 inches below the LEDs.  Par drops to about 80 near the bottom of the tank about 10 inches below the water line. 
		
	
		
		
		
		
		
	
		
		
	
	
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