Sorting Through Contradictory Brewing Advice

TroubleShooting

Thomas Wood — Nicasio, California asks,

Please comment on some seemingly contradictory pieces of brewing advice: 1. It is commonly advised to chill the wort as quickly as possible post-boil to avoid hot-side aeration or bacterial contamination. Yet hopstands delay chilling, and, if you stir to create a rotation, don’t you risk introducing O2? 2. I’m told that once the mash is mixed to let the grain bed settle without disturbing it to form an efficient filter bed and avoid a stuck sparge. Yet people also advise stirring the mash for batch sparges or to stir the mash halfway through the mashing period. So what happens to the filter bed?