well definitely do not do anything strongly basic in an aluminium container. it will form aluminium hydroxide and hydrogen gas. as for the acidic extraction I am not sure. technically you can oxidize Al with acids but I doubt that much of that will happen at pH 3. And when you extract with an organic solvent after basifying, next to no ionic compounds will migrate anyway, and to be sure, you can even wash your organic phase with brine to get it all out.
you could test it this way: boil some acidic water in the pot, transfer that to a glass container and bring it to pH 14 with NaOH. If there were any real amounts of aluminium in the water, they should precipitate out because aluminium hydroxide isn't soluble much in water.
ps solid aluminium metall is covered by a passivating oxide layer anyway. so in mildly acidic conditions I really think it should be fine.