What are you running in your media box? I have the sponge on top, ChemiPure in the middle, and chaeto in the bottom (nano-glo mounted). It seems as if the ChemiPure is impeding flow if i push the media box flush against the overflow, as it starts to overflow...so I just leave the box submerged but essentially just sitting in the chamber. Anyone else have this issue? I am wondering if I am getting any real flow through the media in this position...?