It normally depends on your what you are thinking of placing inside your QT tank. I'll tell you what i have in mine.
I have a external Eheim canister filter that contains ceramic for bacteria and sponge, then i have a heater inside the tank aswell as a air stone for oxygenation for the water.
I do weekly water changes (if needed) and monitor the Ammonia, Nitrite and PH of the tank.