I'm considering either 180 or 220. Both are 6' long and 2' deep. The 220 is 6" taller @ 30". I've never had a tank deeper than 24" which I could get to the bottom of using just arm (I'm 5' 11" so just reach). How do folks place corals etc on the deeper tanks? I like the idea of a taller water column for both coral and fish, but worry about maintenance/ practicality.