I use RV  anti-freeze in my sprayer. Gets -40 both C&F here, sometimes colder. Yeah, if you go out and look it will be slushed. Doesn't matter though. What you want to prevent is freezing solid so it busts things. When it is slushed, it doesn't create pressure so nothing gets hurt.

Sometimes our vehicle radiators will slush as we're driving. That's no good, as the slush doesn't circulate and the engine overheats. Good way to wreck an engine.