Everybody seems to have a favored solution for but for me it is a 12.5 ph non-residual soap and water but I have used common household liquid dish soap and water with good results just need to rinse afterwards. It will corrode the aluminum if not rinsed off.
Currently I am using a 10L UC which I add 1-2 tablespoonfuls of soap to the water bath and change as needed. This is because a dirty solution will prevent good cleaning action of the UC operation. Also at different time swap around my mix according to what I am having to clean. Sometimes I even use white vinegar to remove most rust.
Just got be careful what you use while experimenting with different solutions as not all UC tanks of the same grade of stainless steel. I had one unit that actually tried rusting if left my soap solution in it overnight. Please avoid using things like fuel or any other flammable liquid to clean with as it is a fire and explosion hazard. To me it is best to drain and clean the tank when though with the cleaning right away.
Also don't every cleaning job to take the same amount time. In my current unit I have time as little 15 minutes up to several 30 minutes cylces. Using heat helps most time especially on heavy oiled items. I seldom go above 50C even though my unit can to 80c. One reason it is too hot for to put my hands in any length time hunting for small parts.
