Floating in water takes some skill. Floating in 800 plus pounds of Epsom Salt solution is not just easy, but impossible not to. You will float. The buoyancy of that much Epsom Salt is high enough to rest you on top of the water allowing the relaxation and muscle stress reduction to happen.
USP grade and Technical Grade Epsom salt are identical. The difference is the USP grade, which we buy exclusively, has been certified whereas the Technical grade has not. They may have even came from the same batch. But we pay more to ensure the batch we get has been tested to the highest standard for consumption or soaking.