I find store bought plugs to be too small and too expensive and racks a nuisance to keep clean. So I made a few hundred of my own 2" disks a few years ago which I just set in the sandbed of my frag tank.
http://www.canreef.com/vbulletin/sho...ment+disks+diy I made a lot of 1" disks as well but I rarely ever use them.