You can keep Xenia with fairly basic lighting. I have a friend that keeps Xenia really well in a 55 gallon with 3 40 Watt Normal Output flourescents. You'll also want to start feeding them "filter feeder foods" such as Phytoplex by Kent, or some other form of "live" food. Rotifers is also another excellent source of food from what I hear, but I have yet to try it.
The most important thing for Xenia I have found is to dose with Lugol's Solution. It's an Iodine supplement. 2 Drops per 40 Gallons, I believe. Read the directions on the bottle for an accurate dosing.