Apogees website shows that when measuring LEDs the readings get progressively further out the lower you go in spectrum.  i believe the chart showed at worst 10% low in the blue spectrum which is admittedly what most of the PAR value is that we get out of LEDs.  but 10% doesnt change the numbers that much. 
 
Dont get me wrong, im not about to buy bigger drivers and try and push the readings higher just because they look low.  if i max my light out the coralline will start to bleach and i notice some corals starting to close a bit.  things just dont seem right, so i go by what my tank tells me. 
		
	
		
		
		
		
			
		
		
		
		
	
		
		
	
	
	 |