While the Redmonds is a natural sea salt mined from ancient sea beds. I do believe that they use anti caking agents. After hearing some folks mention the Redmonds I bought some and did a side by side taste test with the Celtic Sea Salt and to my palate the Celtic was mellower.
As I noted in my personal routine. If you don't feel you are getting all the SWF out. Drink a whole quart of plain water about 1 hr after doing the SWF so if you are retaining some of the salt it will help to keep it diluted and passing out of the system.
I only make my water slightly warm without using a thermometer I would guess it's somewhere at or just a little warmer than body temp.