you know the old trick about putting a load of nuts and bolts through the liks of a small chain(like a sink plug chain) and dropping it in ther tank with some hot soapy water, then wrap it all well in cardboard, old blankets, bubble wrap, whatever you have to hand, and jam the whole lot in the drum of a cement mixer for a few hours, taking it out occasionally to turn it round. alternatively, for rust removal, try googling electrolytic rust remover, you will need some washing soda, some iron bars a battery charger and a few days to wait!!!!
