Troubleshooting Chart

Key: “X”: For beers made with malt extract, “AG”: For all-grain beers

Problem Causes
Fermentation does not start
  • Inadequate amount of yeast pitched
  • Wort too hot (yeast stunned/killed)
  • Wort too cold (yeast dormant)
  • Fermentation fine, but bucket not sealed (so you can’t see bubbles in airlock)
  • Fermentation already complete (look for ring of “crud” around inside of fermenter)
Stuck fermentation
  • Not enough yeast pitched
  • Inadequate aeration
  • Wort temperature too low
  • Yeast strain flocculated early (rousing yeast may help)
  • Fermentation is finished, not stuck (take specific gravity to check)
A puckering, tea-like quality; sometimes confused with bitterness (astringency)
  • X: steeped grains in too much water (over 3 quarts water per pound of grain)
  • X: steeping water too hot (over 170 °F)
  • AG: excessive volume of sparge water (collected wort less than SG 1.008 or above a pH of 5.8)
  • AG: excessively hot sparge water (over 170 °F)
Sour or tart beer
  • Contamination
  • Tart ingredients (like raspberries or cranberries)
  • AG: mash sat overnight and temperature dropped to 120 °F (or below)
A buttery or butterscotch-like flavor or aroma (diacetyl)
  • Yeast did not absorb diacetyl (a diacetyl rest is required for some lager yeast strains)
  • Contamination
  • Racked beer too early
  • Yeast strain
Overly fruity aromas, especially banana (estery)
  • High fermentation temperatures
  • Inadequate pitching rate
  • Yeast strain (some British and Belgian ale strains are supposed to be very fruity)
Chloraseptic-like or Band-aid-like aroma or flavor (phenolic)
  • Contamination
Vinegar flavor or aroma (acetic)
  • Contamination, especially in conjunction with exposure to oxygen
Wort darker than expected
  • X: concentrated wort boil
  • X: scorching of malt extract (stir in thoroughly)
Stuck mash
  • Running off wort too quickly
  • Grains crushed too finely
  • High percentage of wheat or rye
Low extract efficiency
  • Crush too coarse
  • Collecting wort too fast
  • Collecting too little volume of wort per unit of grain
  • Poor lauter tun design
  • Water chemistry not conducive to good mash (check calcium levels first)
  • pH outside of 5.2-5.6 range
Overly high final gravity (FG)
  • Maybe the beer was supposed to have a high FG
  • High percentage of specialty malt in recipe
  • Yeast strain
  • Any of causes listed under “stuck fermentation” (above)
Chill haze
  • Use Irish moss (at rate of 1 tsp. per 5 gallons
  • Boil too short or not vigorous enough
Poor foam
  • Glassware dirty
  • Weak fermentation
  • Too little protein in wort (esp. when high amounts of adjunct are used)
  • AG: overly-long rest at 122-131 °F
Mold on surface of beer
  • It may be yeast, not mold (different yeast strains behave differently)
  • Wort is exposed to oxygen, which encourages surface growths
Bottle-conditioned beer is flat
  • Move bottles to warmer location for conditioning
  • Give beer more time to condition
  • Beer and priming sugar not adequately mixed in bottling bucket
  • You forgot the priming sugar
  • Not enough yeast left in beer to bottle condition (rarely happens)
Bottle-conditioned beer is overcarbonated
  • Contamination
  • Beer and priming sugar not adequately mixed in bottling bucket
  • Too much priming sugar
Beer’s original gravity (OG) too low
  • X: wort and topping up water not mixed thoroughly
  • AG: poor extract efficiency (see above)
Cheesy aroma or flavor
  • Hops are old and stale
Corn-like aroma or flavor (DMS)
  • Wort cooled too slowly when certain very pale malts used
  • contamination
Solvent-like or nail- polish aromas (higher alcohols, fusel oils)
  • Fermentation temperature too high
  • Inadequate aeration
  • High original gravity
Skunk-like aroma
  • Beer exposed to light (especially due to bottling in clear or green bottles)
Wet cardboard aromas and flavors (oxidation)
  • Beer exposed to oxygen during late fermentation or conditioning
Sherry-like aromas or flavor (oxidation)
  • Beer exposed to oxygen during late fermentation or conditioning
  • Long aging of high-alcohol beers (appropriate in some cases)
Excessive sediment in bottle conditioned beer
  • Some sediment is always present
  • Let beer fall clear before bottling
Water, wort or beer on floor
  • Be sure all valves are closed before transferring liquid to a vessel
Beer on ceiling
  • Fermentation lock clogged (use blow-off tube next time)