ya, the rock will be fine in the tub.  I have a few pounds of rock sitting in a tub right now with a heater and Koralia 1 circulating the water.  The rock is waiting to be put into a new tank.  Lots of pods swimming around in that tub with no predators.. hehe. 
 
K. 
		
	
		
		
		
		
			
		
		
		
		
	
		
		
	
	
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