I have something similar on my system which I thought was great until the detritus started accumulating. I realized how much more effective water changes were when I siphoned out the detritus compared to just draining the water. Even blowing up my detritus into the water column was not as effective.
Having a barebottom tank makes it easy to just blow it off the rocks and bottom or do this with BareBottom cleaning tool [video=youtube_share;249j6nBawWs]http://youtu.be/249j6nBawWs[/video]