By "ions", Blast means "dissolved solids". Technically "salt" does not exist in salt water, just sodium and chlorine ions. Practically, when the water evaporates or boils away, the solid salt is left behind.

An engineer and a scientist were challenged to a race. The prize was a beautiful woman for the first one to reach here. The scientist explained that there was no point in trying, because to reach her he would first have to cross half the distance. Then he would have to cross half the remaining distance, and so on.

The engineer said "You may be right that I can never actually reach her, but I think I can get close enough for any practical purpose."