Re: copper fouling!!!
CHW is correct about ammonia-based copper cleaners being kinda hard on aluminum.
But if used as per the instructions (don't leave it on too long and make sure it's all removed when you're done cleaning) it's not a problem.
If you leave the stuff on too long, it'ill etch into steel too. Yep it's potent, but if you've got heavy copper fouling ammonia is the stuff to use.