teacherspet
Fish Fanatic
I also thought the bio wheels were for biological filtration and the cartridges were for chemical and mechanical.  I have a bio wheel and a filter with two slots for cartridges.  I rotate a new one in and an old one out every month without disturbing the biowheel.
				
			 
	             
 
		 
		


 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		