Not very practical in terms of possibilities of in-home aquaria, but when I went on a behind-the-scenes tour with the Monterey Bay Aquarium vet a few years ago, I remember him saying that they had a lot of trouble getting their jellyfish exhibits to work. I honestly don't remember the details, but I do remember that corners was part of it, as well as figuring out the whole waterflow thing where they wouldn't get blown into corners, or having stagnant spots in the tank. The water runs in a circular (oval?) flow around the tank - I believe that there is an intake and an outtake on opposite sides to send the water up the rounded side and around again. If that makes any sense. I do not recall what he said about lighting.
Pretty much the whole aquarium is run off of feeds from the Bay (unless they've got a red tide or something going on, where they use filtration systems that are set up as backup to recycle the water), so they've always got fresh ocean water coming in for all their tanks, and I expect that factors into their success as well...
If I recall, the tanks appear rectangular from the front. But they're not really... here's the couple pictures I took... first one is from behind, 2nd is from the side of the tank (I appear to have rotated the picture shortly after the trip (since vertical is how I saved it on my computer), but looking at it now, I'm not sure that makes sense, as all the jellies are upside down on the display side), and the 3rd is what the general public sees. and all the jellyfish tanks are the same, except some variation in size for a few, IIRC.
Sorry I don't recall more details - I'd been up since 4am that day, we went whalewatching in the morning (saw some dolphins, I got seasick for the first time in my life), and then the tour was in the afternoon, and while it was interesting, since there was little that I was planning on applying practically into my life, I took as "that's pretty neat" but didn't really take notes or anything. Sorry I didn't take better pics of the setup, but again, at the time, I wasn't interested enough to do that...
