best soaking carb cleaner?

Yup.. I bought an ultrasonic tank four years ago, cleans as well as the old dip tanks without destroying the finish... Gets all the passages clean... Carbs that wouldn't run right after soaking & kitting suddenly have a new lease on life...
What do you put in for the cleaning fluid? Is it heated? How long does it take to do its thing? What ultrasonic did you buy, brand and model number?