I heard that you should never use aluminum given the magnetic properties, or lack there of, of it. Stainless will attract a huge number of finite impurities in the beer, actually cuasing them to stick to the metal, and, in affect, filter them out. Aluminum won't, allowing all of those impurities to stay in the beer during the mashing process. Then, if you BOIL in aluminum, you're basically magnifying the problem ten fold as the boil intensifies the problem by evaporating water, concentrating all of those impurities.
Most of these impurities come in the form of giardia lambia, cryptosporidium and selenium. The HUGE problem with these is that the liver had an extremely difficult time filter these things out of you system once you've ingested them. If you end up drinking a lot of homebrew (and who among us doesn't?) you'll end up with huge quanities of these things in your system for long periods of time. Side affects of having a large concentration of cryptosporidium in your system is excessive gas buildup and lowered sperm count. Giardia lambia will cause loose bowels syndrome and possible anal leakage. Selenium leads to poor muscle control, fatigue, low blood pressure and nausia.
Add poor muscle control to excessive gas buildup, loose bowels and possible anal leakage... combined with low blood pressure and low sperm count and you'll be walking around with no ability to get it up, while you fart and sh!t all over yourself every ten minutes. No woman would ever want to be near you when you smell like that but even if she did, you couldn't get it up and if were were able to do THAT, you would be shooting blanks.
So for God's sake... PLEASE... don't use aluminum. Or you'll be an impotant diarrea shooter.
I read that somewhere.
True story.