You might try this stuff.I've used it to take out rust stains and it works quick too.
http://www.whink.com/index.cfm?fuseaction=cEcommerce.Product&ProductID=4328&CategoryID=1535

~Molɔ̀ːn Labé Skýla~
As Bob Hagel would say"You should not use a rifle that will kill an animal when everything goes right; you should use one that will do the job when everything goes wrong."Good words of wisdom...............