Tricky

I am interested in adding Dead Sea Salt to my Arctic Spa 880 litre hot tub but am concerned about the effect it may have on water chem. I found footie's thread from 2011 with Chem Geeks comments but am not sure I got all the information I would like. What happens if I add the dead sea salt to a chlorine treated tub? What would the effect be on water hardness? Is the ppm for dead sea salt the same as for other salts used in hot tubs? From that thread ~600 ppm ( I assume TDS) would be okay but that seems low for most salt systems that I see suggested from internet searches. I contacted my hot tub supplier and the tech there said they suggest their salt systems be 2150 - 2520 ppm. Any comments would be appreciated.