Advise on revamp of 200 gallon tank

Hi everyone--

I figure many of you are here because you enjoy giving input to
others. So here we go: I'm taking control of a 200 gallon aquarium
which is currently running in the classic and awful sterile fish-only
style. Green and blue algae are everywhere, the remaining (I stress
remaining) fish look marginal and there is zero other life in the
tank. The caretakers (enthusiastic but busy and non-fish-buffs) are
health care professionals, and the tank is in a radiation therapy
waiting rooom. This tank is truly awful. The worst part is that it
was funded by donations, and it is a total embarassing waste of money
as it stands. My job: make this thing into a very low maintainance
reef, that can eventually be passed on to non-marine biologists.

My biggest design issues involve plumbing without using a sump. I
would really, REALLY prefer to avoid a sump. Floods are really not an
option in this place, and rushing/gurgling/slurping water isn't a
great thing either. Am I being paranoid about a flood? Perhaps.
Maybe I should use a sump. I dont know. Thats why I'm asking you
all.

The tank is currently drilled 5 times through the bottom, all along
the length of the middle of the tank. 4 intakes feed two Iwaki 70
RLT's, via the most goofy and restrictive combined intake system you
coul imagine. They both feed through a 3/4" return line (yes, thats
right, a single line). And did I mention the pumps are pulling
through an undergravel filter? Yep. And did I also mention that
somehow the tank reached 90 degrees recently, prompting the purchase
of a 1/3 horse drop-in chiller? (which is just a lovely sight, sitting
there on a table with a huge black hose and coil dropped into one end
of the tank).

The more I write, the more I think a sump is inevitable. I can't
stand hang-on gear, and it would look especially goofy in this setup,
as the tank is visible from 3 sides. Now I suppose my mission is to
install an overflow system on the tank. Any suggestions on where to
buy a central overflow? Build my own?

I'm getting overwhelmed thinking about this. Time for bed.
Thanks for any ideas,
Ryan Lenz