aluminum for electrolysis?
You will rapidly form aluminium oxide, which will coat the positive electrode. After a while, this will diminish the current, so the efficiency of the electrolysis will be greatly reduced. The electrolysis itself is fairly safe (it is how anodised aluminium is made). But you'd be better off with a less reactive metal as your electrode, or one which does not form a protective oxide layer (or at least, not as easily).