It is my understanding that the magnesium chloride oil from the Zechstein Sea is in a whole different league when it comes to absorption and bio-availability..than something like Nigari mixed with water. If you don't absorb the magnesium at meaningful levels, what good does it do you? I'm also with Walden99 in my concerns about contaminants when using Nigari. I guess you get what you pay for, but when it comes to health, I usually go with the absolute best quality available.
I have been using DermaMag magnesium oil from Magnesium Direct and it is terrific. As far as I can tell, it is the best product on the market. It is the exact authentic magnesium oil that Dr. Mark Sircus talks about and has the "Zechstein Inside" logo on the bottle, so you know it's the real thing.