Thanks. I'm trying to brainstorm how to mount the pump now. If I used 4" PVC, I might be able to find a pump small enough to fit inside. Don't know yet.
Edit: well never mind that idea. I found an external inline magnetic pump that'll flow 350 gph for about 60 bucks. Even with the PVC, connections, hose and media, this filter will still be quite a bit cheaper than a "real" one!