Troubleshooting Chart

Here are some common problems and their causes that you might experience while brewing.

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

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)