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)

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