Cleaning the tank with vinegar..

[979roadrunner]

Use screws or some such, that way a magnet can assist getting them out

[Nessism]

Use screws or some such, that way a magnet can assist getting them out

In my experience nuts/bolts/screws are too coarse and don't get into the nooks and crannies, and BB's are too smooth to scrub the metal. Aquarium rocks do a great job of scrubbing the metal, but they take some time to remove. You can also use pea gravel, but like the BB's it tends to be too smooth.

Regarding all the techniques discussed here, please understand that unless 100% of the rust is removed, it will come back. Look at the pits in the metal and if you see any orange, keep going with the derusting process. My preference is to seal the tank after derusting to assure the rust doesn't come back. I usually use phosphoric acid to derust since it eats the rust and converts what's left into iron phosphate. Oxalic acid works well too and doesn't eat into the base metal like some other acids. HCl is bad from what I've been told since the Cl atoms bond into the metal and won't stop corroding the metal, even if rinsed. The devil's in the details.

[tkent02]

I tried vinegar on a rusty old hammer, twelve hours worked.
It was about as rusty as a medium bad tank.
I still prefer electrolysis, but might try vinegar on one just for kicks.