Can anyone recommend a good ultrasonic cleaning solution. I have tried the
ones from Rio, but I am not happy with the results. Seems like the cleaner
has to be very hot to be effective. Also, my hands are starting to show an
allergic reaction to the solution. Any help would be great.

Guesswein sells a concentrated cleaner I like but I don't know how it will
effect your allergies. Theres always the old tried and true: 1 part Mr.Clean, 2
parts plain ammonia, and 3 parts water. Doesn't clean quite as well maybe, but
it does work, it's cheap, and the ingredients are pretty mild.