Storage drawers such as this are easily availabe and allow you to have one slide out for mechanical filtration and another for bio-filtration along with a third for chemical or buffer storage.
http://www.stacksandstacks.com/iris-...-303/763/6883/
All you have to do is punch holes in the bottoms of the drawers and have it drain out into a rubbermaid container that holds your pump and any other aquarium equipment you don't want visable in the tank. It makes a very economical wet/ dry sump system.