[Myka]

Since Chaeto does best if it is tumbling you need to either make a cube shape (matching depth of the water) to accommodate a ball, or make a long narrow section to accommodate a hotdog shaped wad of Chaeto. I would suggest when you design this that you consider that your reef should only need the Chaeto in the first year (or maybe down the road on occasion when you're having troubles with nutrients). It is a nice option to have.