Hot side aeration (HSA) is a myth, right? Or is it? I’m sure by now many of you have read the PDF put out by the German Brewing Forum that has caused a bit of a stir. The reactions I’ve read have either been “This changes everything!” or “This is complete rubbish!” with little in between. I don’t want an Apple v. Android style fanboy dogfight. I want to talk facts and figures, science and chemistry. Let’s eliminate the hyperbole and see if we can dig into what is and isn’t really going on here. If you haven’t read the PDF, it basically advocates using sodium metabisulfite (SMB) in the strike water and working towards lowering oxygen ingress at all stages of brewing.