I plan on putting a medium sized refugium on the back of my 30 gallon. It's 19" and I'll position it about in the middle. I plan on have 30 pounds of southdown (whenever I can find the damn stuff) in there. My question is, I figure with 30 pounds in there covering the bottom 4 inches, with another 8" to go to the top, that's maybe another 30 lbs of water or so, will the tank of my back be able to support that? I know that they sell these things, and that all the filters on the back must weight something, but 60+ pounds is alot of weight. Any comments? Thanks