I said: "it isn't a good idea to use for more than a month or two", however I plan on continuing until I'm done detoxing and all my symptoms are gone, even if it takes longer than this. I just take an extra large amount of vitamins. I've read studies showing that it doesn't cause any significant problems from several months of use of very large amounts, so it probably isn't a huge issue. But you probably shouldn't take it any longer than is neccessary.
Get the 1lb size, since you'll likely use it up pretty quickly (within a couple months) if you take 6-12tsp a day.