My freind is looking at changing his 3'x15"x18" fresh water to cichlid next weekend and he has been given a second 1200lhr canister,would hooking them together so the water flows into the first one full of filter wool and then into the second one full of bio-media be a good idea,just thinking the first one would keep the second one full of bio-media cleaner longer and bo a better job, have seen one done this way on one of the sites quit a while back or just run them sperate. thanks.