I think he means to have something like an fx5 or whatever for mechanical and then put a 5 gallon pail above the tank and have the output from whatever canister go into the pail with bioballs or dish scrubbies in it like a w/d and then have an outlet at the bottom of the pail draining into the tank. I have seen similar setups on here before as well. Only problem I see is if a power outage happens than the media will dry out instead of staying wet like in a sump, unless there is a way around this...