I have a Whisper 3 hang on the back filter that contains activated carbon and sponges for bacterial growth (I had it left over from my freshwater days, probably overkill on a 10 QT).
You'll want some type of lighting (preferably on a timer), enough to see the fish (better if you're going to put corals into the QT); I have a 18W fluorescent bulb.
Other than that, not too much is needed. You already have a heater; I have a separate thermometer that I keep in the QT. I painted the back, bottom, and one side of the tank black. I keep a MJ600 in my QT also for some better waterflow (its on the same timer as the light, so it goes off at night). Eggcrate to keep your fish from jumping out of QT.
Its good that you're setting up QT.