After deciding what chemical you want, the second most important factor is applying it correctly. More is not necessarily better, and in some cases can create problems with oily or powdery residues. Most manufacturers direct you to remove the slush after the deicer has done its job; hence the often-used marketing phrase — “safe when used as directed.”
Almost all bagged ice melt contains the phrase, “Safe if used as directed.” The manufacturer instructs users to remove the slush after melting has occurred. We realize this instruction is unrealistic, as well as expensive; but it is the only way a blended product can be labeled as safe. For example, when you remove the slush created from a blend containing 90% salt, you are removing most of the chemical that could damage nearby vegetation.