ultrasonic cleaner solution

Ultrasonic cleaners often work best if the items are isolated from the housing.
Some cleaners shake (excite) the part, others excite the fluid. I think most table top units excite the fluid. If you put a heavy part in, it overloads the exciter and nothing gets to the ultra part of the ultrasonic. Usually there's a plastic basket or similar what rests on the rim of the machine so that the part is isolated from the bucket. You could also hang the part from a wire or string - but it needs to be thick enough that it doesn't erode away while the part is in there!

We used deionized water in our US cleaners in our deburr dept. Only used chemicals if we needed to degrease at the same time, but that stuff was super expensive, so usually it was just water. Other solvents and cleaners can work, but the water typically does most of the heavy lifting. The chemicals tend to work at the same speed, but slightly enhanced because the water is zapping off the dirt and other gunk which often shields the base material, or the chemical strips the oil/gunk what would typically shield the base material from the water..

Basically, don't go overboard with chemicals because a litte but will go farther in the US.