OK, I split this off from the group buy thread...
I think the point is, commercial grade salt is just that...commerical grade. Like Chevy, Dodge or Ford, you have positives and negatives and generally can't go wrong. It is personal preference. All commercial grade salts will keep our animals alive. Will they yield ideal water parameters? Probably not. That isn;t likely to happen until you move to the coast and have a flow-through aquarium plumbed from the ocean. But like I said, any commercial grade salt sold nowadays will keep our animals alive.
My goal is consistency and repetition. I follow the KISS method. I am not a very smart person and i believe most of America is just as stupid as me. I prefer to remove all guess work and chance of error.
Will you screw up your tank by mixing salt? Heck no. Mixing SeaChem and IO or whatever brands does not result in some fatal by-product. But is it an extra step not really worth bothering yes? IMHO, yep. Does it yield higher alk and calcium levels? Possibly, but I have $800 in plastic in my garage waiting to deliver both in excessive quantities so I guess you can say I am not worried about make-up water testing 375 or 450 on calcium, etc.
JMO