The only thing I would really like to change about mine is that the filter pads I use are in the back corner and they are kind of a pain to change. I wish it was in the front.
Also, I don’t actually use the refugium any more. I had chaeto in there for a while, but it eventually died. I’m able to keep my nutrients under control by running my nano skimmer 6 hours a day. I don’t have any nuisance algae in my display. I wish I could grow chaeto to help raise my ph, but at this point it’s not worth the effort.