I had exactly the same thing happen to mine while in QT: first on the power head, and then on the intake for the canister filter! 
 
I pulled the power head out and reduced the flow on the canister filter. Then I watched I'm like a hawk for an hour. 
 
How much flow do you have in your system? 
 
I'd put him whatever system has the least amount of flow. 
		
	
		
		
		
		
			
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				Shelley
			 
		
		
		
		
	
		
		
	
	
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