Tips and Myths:Aluminum Pots
It is a tenacious and persistent belief that one cannot brew in an aluminum pot. Several studies on aluminum pots have been made in the past five years and it has been determined that there is little reason to fear that aluminum will have a detrimental effect on your beer.
So if you are on a budget it probably won't hurt much to use an aluminum pot, as they are cheaper than stainless. Also the theory that aluminum has a casual effect on alzheimer's disease has also been disproven. We would say that bi metal or stainless pots are better because they display better heat transfer characteristics and are more durable. You might take note that a HEAVY ceramic canning pot is just fine.