JeffMuse;640389 wrote: If you have a very limited area to work under the stand, I would go for a nice skimmer over a refugium. I think that a fuge will certainly help keep your nitrates down and add a few other benefits as well; however, nothing can replace a good skimmer. When picking a skimmer, look at the foot print of the unit you are buying... this will show you the actual amount of space that the skimmer will take up in the sump.
Another thing to keep in mind is that it is sometimes better to go with a smaller sump and plumb your return pump externally. This will help dramatically with keeping the temps in the tank lower.
As far as height goes, you want the sump to be fairly high as the more water volume the better. Keep in mind though, that you are going to be doing a lot of maintenance in this area, so you need to have room to work under the stand (don't make it too high

)