I know a few things about using ultrasonic for cleaning parts, and can offer a few general tips.

Whatever you're cleaning, it will need to be broken down into its various parts. The solution needs to be able to carry away the crud it's removing, and fully assembled, enclosed things won't allow for that. As for time, let the stuff you're cleaning tell you how long. Let it go for 5 or 10 minutes and then take a look. If the parts are still dirty let them go for another 5 or 10 and then check again. For stubborn residue use an old toothbrush where needed.

Also, you don't need to fill the tank up with the solution you are using. Fill the tank with water, and then put the solution into a glass or plastic container along with the parts you want to clean. The ultrasonic waves will pass through the walls of the container and do their thing inside where the solution and parts are. This keeps your tank from getting nasty. You'll need to place the container into the tank when filling with water so you don't cause an overflow when putting container into the tank later on.

Purple Power, Simple Green, dish soap - all those will work fine on their own. Just pick one and go with it. You can use a pretty weak solution and still get good results. When done cleaning rinse with water and blow the parts off with compressed air. Lay them out on a clean paper towel to let them dry completely.

You'll like having that ultrasonic tank. They come in handy for all sorts of things. I work on watches and cameras, and I use my machines for all sorts of stuff.