Well i just bought Kelp because it was all I could find...but then I read this:

Kelp Tablets, for example, contain only 225 MICROGRAMS of iodine! (Fortunately, it is also available in a 1000 tablet bottle, unfortunately though, you'd need to be swallowing 442 of them per day and likely not wander too far from a bathroom!)

[link to www.ki4u.com]