I have a plenum in my 125 that has been running since '93 and wouldn't run that tank any other way. I also have had tanks with just 1 - 2 inches of course sand directly on the bottom and my next experimental tank i'm thinking about going bare bottom with a remote plenum/refugium, just to try it. there are many things to consider with sand and many options available. If you want to do a plenum - do it - just research it and do it right, like so many good ideas gone bad in this hobby, there are a lot of myths and misapplications of the system out there