Oops... I used Comet on my Aluminum brewpot

Yeah... I'm usually more cautious than this. I let my aluminum brewpot soak for an hour or two with hot water and Comet. You know Comet, it's that powdery cleaner that comes in the green canister. The one that says "Don't use on aluminum." Anyway, now I have these dark gray splotches on the inside surface of my brewpot. It doesn't look good. I guess I should have read the package beforehand. Should I use this as an excuse to buy a new brewpot?

 

Sand it down to bare aluminum using progressively finer grits. Fill with water and boil for an hour. Next time use mild dishwashing liquid and a soft rag to clean it.

 

Of course. I bought my brew kettle off of Amazon and got a SS one for cheap. In fact, both that I have bought have been from Amazon. My 9 gallon one (current) was $60 I believe and it is SS.