my reflectors are about 10inches off the surface, so i guess the bulbs would be about 12inches...I guess the higher you go the better the spread but less intensity.  My actinics are about 8inches off the surface.  When i was reaserching how high to put my halides, the general consensus i found was about 8-12inches. 
		
	
		
		
		
		
		
	
		
		
	
	
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