Well it does ofcourse revolve around the thickness of glass but I wouldnt want that huge thing hanging on my little nano. Those are used for 50ish or so gallon tanks. I would aim for a hidden cheapo 10 gallon refugium on a 15 or so gallon nano.
geesh guys,
I had an aquafuge 19x12x4 or something like that on a 29. Worked well, no problemos. Added a bit of gallonage and nice safe place for pod production. Put on a light with reverse lighting and you shouldn't have any heat problems and you could also put your heater in there.