Keep in mind epoxy is not glue and will not stick to rock. It's designed to be used to wedge a frag into a space and harden in place, physically binding the frag. It won't stick to flat surfaces, so make sure you've got a rough crevice or indentation to mount to.  
Also, most (all?) putty you'll find at the hardware store typically has metal shavings in it, not approriate for reef use. 
		
	
		
		
		
		
			
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				Brad
			 
		
		
		
		
	
		
		
	
	
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