Hi all. I bought a cheapo (£24.00) sonic cleaner from Maplin’s at the beginning of the year (2010). Not too impressed at first so I read up on how they work and what the differences are between the cheapo’s and the one’s the rich folks like Bob use. 
Things to look for/out for/think about.
1. Temperature/adjustment/controll of cleaner/liquid.
2. Liquid used.
3. Degassing.
4. Cavitations.
Working in reverse. Cavitations are formed when ultrasonic travels through any liquid. IE: When a sound wave travels through water it deforms the molecules as in pulling/pushing. When the frequency of the sound wave reaches a certain point it literally rips the molecules apart and zillion’s of bubbles are formed under pressure. The bubbles expand until they pop and that creates zillions of tiny explosions. This action releases a huge amount of power. I read somewhere that the boffins say that every single bubble has a temperature of somewhere around 4-5000°C. Plus an estimated pressure of around 9-10,000 PSI. Think about that the next time you blow a bubble with your gum 😆
Degassing. The bain of sonic cleaners. 
When I develop black and white film I use distilled water (real hard water where I live) as I have found that I get crisper negs and….no drying marks. If I’m just developing a test roll (restoring old cameras is another hobby) I’ll use tap water but I let it stand over night to degas.
Degassing is the removal of gases present in the solution. Cavitation will be much better after gasses have been removed. Unfortunately: Most of the cheapo cleaners have no degassing system so fill up a ?lt container and let it stand (cover opening lightly with a tissue) over night.
Water water everywhere and all the boards did shrink…..
Well. That’s all you’re supposed to need. Just plain old tap water. But: degas over night or use distilled water + a few drops of fairy liquid and see the difference (see temp notes) between the water only clean. Some sonic cleaning manufactures recommend special solutions but I’ve heard they can leave a residue and the one I’ve tried didn’t do as well as my cheapo distilled water and fairy set up. Make sure you give the parts a good rinse. I wash the tank out and do the above process again but omit the fairy.
Temperature.
I found that by turning my machine on for 8/10minutes before I dunk the parts in it I get a much better result. Guess that temperature has its part to play and some say that… 50-65 deg’s is the dogs! Have to say it gets better with a bit of heat.
If you want to see how your sonic is performing then….take a glass slide and wet the frosty side with ordinary tap water. Draw an X with a pencil (I read that a No 2 is best? Thanks to Nicolas-Jacques Conté 1755-1805) from corner to corner of the frosty area. Place it in your tank (set up your tank as you would normally) then turn on.
The X should start to fade/disappear almost immediately. My tank takes just over 10sec’s to remove it completely (tank warmed up, distilled water and a drop of fairy liquid).
I try not to use the plastic basket as I think it reduces the effectiveness so I made up a plastic frame that looks like the head of a tennis racket and I hang parts off it on 12lbs fishing line taking care with spacing so as to avoid the parts hitting each other. Might seem a bit of a palaver to some but I think the repairing/restoring of a watch, any watch, is a 100% effort all the way down the line and the cleaning is just as important as the choice of oil, maybe even more so?
Apologies for the saga. Just thought you might find it of help. Mind you, if you think is long wait until I write about Tweezers! 😮
Man, there are some real crummy ones out there! And some are….. Non Gradus Anus Rodentum! so…….Caveat emptor!
Happy new year folks!
Scott.