Are aluminium pots acceptable as boil vessels? They're cheap, but I've heard they can produce off-flavors. Any experiences with them?
I have an aluminum pot that used to be my boil kettle; now it's my hot liquor tank.
The old thought was that it either caused off flavors or, even worse, contributed to Alzheimers. Neither is true. You can't use caustic cleaners on Aluminum, but otherwise it's safe.
BYO covered all sorts of metals over on their site.
If using an aluminum turkey fryer, make sure it hasn't been used for, you know, frying a turkey in the past. I made that mistake once (trust me, I cleaned the heck out of this thing before starting) and I'll never do it again. You'll end up with the worst tasting beer you've ever tried. It was a tried and true recipe for me, so I knew it would have ended up great. It may have been the aluminum that gave it the off flavor, but I'm thinking it was leftover turkey-frying residue.
Anyways, I use all stainless steel, and you can't go wrong there.
I've used an aluminum pot for years. Admittedly, it is not as structurally strong as steel, but a decent gauge aluminum pot in the sizes we're talking about will NOT deform under the heat of brewing, even after a decade or more. (Don't do this with an industrial-sized 30-bbl kettle.) The thinnest ones that come with some turkey fryers are quite dentable -- but so are some stock pots.
You can't use caustic cleaners on aluminum, so beware of that. But it's the boil pot, so it doesn't have to be spotless to be sanitary, and a white scrubby takes off any goop that won't come off with a hot water rinse. Aluminum oxidizes so rapidly that you'd be hard pressed to scrub it and then brew soon enough to get any dissolved in before the oxide layer forms. (Yeah, you could scour it under nitrogen or CO2... but who would?)
As for Alzheimers, not only does the relationship not seem to be causal after much research, but you can't get much if any aluminum on the beer from the pot. Anyone worrying about that better be drinking RO water and avoiding Maalox and some other antacids like the plague! Oh, and don't eat out, either, since aluminum pots are everywhere in restaurants, and for good reason, given the good heat conductance and lightness of that metal.
I'd say make the investment and go with stainless. Aluminum is weaker and less elastic than steel, so it will deform faster, especially on an electric stove (where the heat and pressure come from the same source, which has a small surface area). Good aluminum cookware (if it exists) probably wouldn't have this problem.
I've had good luck with an aluminium pot (a turkey fryer in my case). The pot was big and since it was something that I already owned, it was a solid piece of brewing equipment. We upgraded to a stainless steel pot only b/c we had a close friend that would not drink our homebrew b/c of Alzheimers fears with aluminium. Since brewing is all about sharing with us, we upgraded. I'm not sure what you have/need for brewing equipment, but I would not recommend upgrading your pot before getting some more important brewing pieces (i.e. secondary, temp control, yeast starter).