You want the whole brew to finish in about 3 to 4 minutes. If it's running too fast—say, 2 minutes—your grind is too coarse. That gives you a sour, weak cup. If it's dragging past 5 minutes, your grind is too fine, and you're probably pulling out bitter compounds.

A medium-fine grind, like table salt, is a good starting point for most pour-over setups. From there, adjust based on taste. If you're buying pre-ground, you're stuck—but most home brewers find they get better results with a burr grinder. Not essential, but it helps.