Ultrasonic bath solution - What to put into ultrasonic bath (Aug/06/2010 )

Hello,
maybe a very stupid question, but we have no experience with ultrasonic baths.

We recently bought one, for cleaning spectrophotometric plates (and our glasses while we have it) and it only had some leaflet in chinese. We are not sure what to put inside. Wiki says water is better with a surfactant, but we are not sure what to use. The material to be cleaned is made from glass and is only slightly dirty (DNA, protein contamination and dirt from glasses).
Does anyone have experience with this?

we sonicate with water filled in the sonicator it and works fine!!!
make sure u keep changing the water.. thats it!!

a little bit of triton x-100 or some other detergent (like alconox) won't hurt but don't forget to rinse well afterwards.

distilled water is what we use in the sonicator, works fine ..