the black box is a wet dry. it has a sponge on top and full of bio balls. i got all excited to hook this thing up to my 30 but i was already in the middle of building a sump for it. stopped by the LFS and decided they could use this thing more than i could, so i will be dropping it off to them tomorrow. thanks for all the input, but i think i am just going to go with my original plan. i will say though, it is always fun to get a new piece of equipment for free and try to figure out where and how to use it. thanks again