We have found that pure sodium chloride has zero water retention.
These claims have been made before and most likely stem from the age of Salt pills.

I would also like to point out that minerals in salt are not as bio-available as those in mineral water.

For all those sceptics, do what I did, buy some pickling grade coarse salt and add that to your choice of salts... after that you can try to figure out why the body wants what the body wants..

I heard repeated that the grey in grey Sea Salt is French mud.

I have been using Redmond's Real Salt but I'm gonna try the pickling salt next. Perhaps running it trough a coffee grinder first.

I don't confuse myself over this salt or that, rather look at the mineral balance of the oceans and choose KCl as my salt because there is plenty of sodium in most foods and diets are generally deficient in K so I get a little extra. When I want trace quantities of rare earths like praesodymium, et cet., I'll read about it first before just going out of my way over some or other exotic sounding salt that has 20 ingredients which are foreign to me. If its not exotic, then its kinda normal and who wants that in today's world of marketing ? Besides, since "alternate health" is about being different I can understand why people try different things. It does open up the question of the role of rare earth metals in our bodies' metabolism. Trying new things is how we learn of course but there needs to be more to it than merely ingesting a cocktail of rare earths.