I used to take the NOW brand of Norwegian Kelp, but is was not as fine as I would like, but it seemed to be good quality and seemed to produce good results!
I found a way to buy the very fine ground Kelp for human use directly from an importer, but I had to buy a pallet of it to do this because they only supplied to Distributors in large quanities!
But I just bought an extra Freezer and put it in for me and my family and friends to have to use for the next several years!
I do not know who the different distributors are who supply this fine ground Kelp to the public, you will just have to shop around!