I don't understand your post.... there is a sump, with a submersible pump, with a wet/dry sitting on top. The cans are mostly for additional mechanical and chemical filtration, as well as additional surface movement. The wet/dry does mean no filter socks can be used, but the cans offer all kinds of room for mechanical and chemical media.
Flame away, but I think a 300 gallon tank needs to have a sump with submersible pumps in it...(and a resident rubber ducky if you REALLY want clear water).
