Missing Your Original Gravity
Once you have your OG estimate and brew the beer, you often miss. Occasionally the OG comes in high, but more often your original gravity will be lower than you predicted. So what do you do next?
I’ll cover how to adjust your OG using dry malt extract or water below, but as you plan your next batch here are some of the potential issues to look at:
Grain Milling – For all grain brewers, poorly crushed grains can have a large effect on original gravity. Your grains should be crushed finely – with the center of the grain forming a fine powder. Large pieces of the husk should be left intact, however, to form a bed for filtering during the lauter. A dual roller mill like the Barley Crusher (full disclosure – we sell these) works best for crushing your grains.
Sparging – If you sparge too quickly, have a poorly designed mash tun filter, or sparge the wrong volume you can get a low OG. Take your time when sparging, which will let the wort extract as much as possible from the grain bed. Also design of the mash system can have an impact. A cylindrical (Gott or Igloo style water cooler) with a full size false bottom (screen type) will generally yield higher efficiency than a flat picnic cooler with only a few copper tubes acting as the filter system for example.
Measure your Volumes – If you have not accurately measured your volumes at each stage in the brewing process and accounted for losses along the way, it can have a huge effect on your OG. For example, a 10% increase in final volume can result in a 10% decrease in OG. So to hit your target OG, you also need to hit your volumes at each step – into the boiler, post boil and also into the fermenter. If you find your volumes don’t match your equipment profile – then adjust your equipment profile until you have a good match with your brewing style.