I have a barebottom
You can always get things to grow over a bare bottom. It's not fast nor easy, but it can be done.
You have a few options if you don't want live sand:
- starboard, which many people do, in order to help get things to attach to it. The downside is that you'll get stuff that accumulates underneath it. The upside is that it'll protect the bottom and will reflect light.
- You can also put small islands of live rock, and whatever coral to grow on that, then onto the glass.
- You can make a permanant sandbed, by mixing it with epoxy and covering the bottom. There are a few tutorials on reefcentral that show how people are doing this.