You can certainly use aluminum... First you will want to make sure there is a protective oxide (dull grey) coating on the inner surfaces of the pot though. Fill er up with water and boil it for a short period of time. You dont want a shiny finish in contact with your beer, you COULD (not will) have a slightly metallic taste to your beer. I have always used aluminum, no problems with it yet. Then again, I was never right in the first place, so it is hard to tell?
When you clean it, dont scrub it, just use a mild dish soap and a non abrasive sponge or towel. You want to keep that oxide coating on there bud.