As for the Mandarin I have 20lbs of rock. A feeding station with 2 copepod hotels that is surrounded by live rock. I have a sump which will be filled with dragons breath. Which is for the ruby crab and any other herbivores. I also have 2 gallon jugs for colonies of copepods. Almost forgot a 1/2 gallon of phyto.
So in total I would have 4 colonies of copepods. Including his feeding station.
You generally want about 50-60 lbs of live rock to maintain a copepod population that can sustain a mandarin. They eat well over a thousand each day, and will quickly starve with less. Some people can get theirs eating frozen, but it would need feeding at least four times a day for it to work.