If you've ever noticed that our reef salt cakes up when exposed to air, then that Is a perfect example of why you shouldn't use "regular", salt. When was the last time that you saw salt in a salt shaker cake up?...never! That is because it has additives to keep it from doing so amongst other stuff. So basically, "regular", salt or pool salt has stuff u don't want in it and it doesn't have stuff that u need in it. I'm not a scientist, I'm just saying...makes sense right? If it was all a marketing scheme, I'm sure public aquariums would use "pool", salt lol
My thought is, if your going to attempt this hobby, don't be half fast about it. The things we house in our tanks are much more sensitive than pool salt has the capability of sustaining.