Wow, a 200 gallon tank! The first place I’d look is in my wallet. For saltwater, the tank is the cheap part. It’s all that extra stuff that will cost mucho dollars. In our neck of the woods (central New Jersey), a 200 gallon tank is going to result in a 200 – 300 dollar a month electric bill. If all you have is the tank, all that extra equipment: a sump, pumps, lights, protein skimmer, powerheads, plumbing, etc, etc, etc….on the cheap (and buying used), at least $2000.
I hate to sound like the grim reaper, but you might wish to wet your feet in, lets say a 20 – 55 gallon tank to see if it’s something you want to do. It’s not only a money hole, it’s a time sucker as well…every day maintenance. I’d rather see you check out your interest on a smaller, cheaper tank than go hog wild on a big tank. If you find that it is something you want to do, then you could use this smaller tank for your sump on the big tank.
I’m done with my doom and gloom speech…The first thing you need to do is read, read and read some more. That’s my best advice.