Ultrasonic cleaning>what cleaner?

I've cleaned one of my Guzzi carbs in an utrasonic cleaner (one to go) using a drop of detergent and half a dishwashing tablet. The dirts all gone, but the alumin(i)um has gone to quite a dark colo(u)r now, and it doesn't look as good as before in that respect.

I can shine them up by hand, but is there a solution/ cleaning medium that will brighten them up without disolving the alum(i)nium that I can use in the ultrasonic cleaner?

The other obvious option is to soda blast/vapour blast, but I want to try and avoid this if possible.

Reggie

I used Simple Green HD, the purple stuff. The green stuff will eat metal. I did it about 50/50 which was way stronger than they recommended. Worked fine. I also have the heated cleaner so that helps too.

Dishwashing tablets can be decidely caustic, so you were lucky it didn't eat the carb ?!!

Thanks for the above info. The carb is intact thankfully despite the dishwasher tablet