I have been involved with aquariums on and off for 30 years (both fresh and fish only salt water). I currently have only a 20 gallon fresh water tank, and am waiting for the last few fish to die from old age before I make a decision about where to go next. I'd like to go back to salt water, and am toying with the idea of a fish only with live rock system. My previous salt water experience involved a 45 gallon fish only with bleached coral only, so the live rock would be a new experience. I'd be interested in advice on the appropriate filtration. I'll probably get a 50 gallon tank. Do I need a refugium or can I use canisters or some simple kind of wet dry? Thanks to all.