I am the top dog on my ship in the USCG when it comes to keeping the ship loking good, and the grit used on our sand paper and sand blasting grit is aluminum oxide. One BIG BIG BIG thing to remember is that rust on steel is oxidation, and although aluminum cant rust, but it does oxidize in its own aluminum way. I dont recommend ANY type of metal or metal by-product in an aquiarium with the exception of brass, as any other metal WILL continue to break down over time. NO NO BAD DOG!!