You just have to be sure to condition your aluminum pot before you boil your first batch. You can do this by filling your aluminum pot with plain tap water and boil for an hour in the new pot. Also, you don't want to clean the pot to a shiny brightness after you brew - basically hand wash with mild dish detergent and a non-scouring sponge works really well. The only time you can get metallic a taste is when you boil in a pot you haven't conditioned. I use an aluminum turkey fryer and it works like a charm.
Happy Brewing!