GFO and carbon require different flow rates. If carbon tumbles at a rate like the GFO, it may break into pieces and release into the water column, possibly causing HLLE.
I'd use the TLF reactor for GFO, and get a media bag for the carbon to place into a high flow area in the sump.
I've used the MJ-1200 for my TLF Phosban 550 reactor.