even better than bio balls use LR rubble i ditched my balls a year ago and replaced them with rubble just a thought, and yes they are nitrate factories IME but if you give them a swish in water to knock off the detritus every now and again they should be fine 
		
	
		
		
		
		
			
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				always just 2cents until im broke
			 
		
		
		
		
	
		
		
	
	
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