I also have he marine magic doser, and couldn't be happier. It's been running for 8 months now.  
 
Are you dosing all of your alk at the same time? If so that could be causing a swing in your ph. Also dosing the alk at night every couple hours will keep your ph more stable. 
		
	
		
		
		
		
		
	
		
		
	
	
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