# Troubleshooting Playbooks This page provides structured diagnostic playbooks for the most common brewing problems. Each playbook covers: how to confirm the problem, likely root causes in order of probability, immediate containment actions, and changes to make next batch. For off-flavor diagnosis, also see [Quality Control & Off-Flavor Diagnostics](https://docs.brewfather.app/brewing-knowledge/quality-control-and-off-flavors). > **Brewfather Tip:** Brewfather's batch **Readings** log (gravity, temperature, notes) and batch step annotations create a timestamped record that makes many of these diagnoses straightforward. Consistently logging OG, fermentation temperatures, and FG readings will let you quickly cross-reference against these playbooks. *** ## Playbook 1: Low Mash/Brewhouse Efficiency ### Confirm the Problem * Measured OG is significantly below target OG (>3–5 points on specific gravity scale, e.g., measured 1.042 vs target 1.050). * Pre-boil gravity is also below target. ### Decision Tree ``` Is pre-boil volume higher than planned? → YES: Volume dilution is the cause. Boil longer to reduce volume and concentrate wort. → NO: Continue... Is the grain crush adequate (husks mostly intact, endosperm well broken up)? → NO: Adjust mill gap (often ~0.9–1.1 mm for many two-roller mills; tune to your system). → YES: Continue... Did conversion complete? (Iodine test: no blue/black = conversion complete) → Starch present (blue/black): Mash temp too low (<62 °C / 144 °F) or time too short. → YES, conversion complete: Continue... Is mash/sparge pH and sparge temperature controlled? → Runoff pH rising toward/above ~6.0 and/or very hot sparge water: higher tannin extraction risk. → Mash pH >5.8: beta-amylase activity and fermentability can suffer. → Continue... Is grain bill measured by weight, not volume? → Volume measurements of grain are unreliable. Always weigh. ``` ### Immediate Actions (Current Batch) 1. If pre-boil volume is high: extend boil time to increase gravity through evaporation. 2. If wort is in fermenter at low OG: add dry malt extract (DME) dissolved in boiling water and chilled; add to fermenter and mix well before pitching. (Calculate: \~0.45 kg / \~1 lb DME per 20 L raises gravity approximately 8–9 points.) 3. Note measured OG in Brewfather batch readings — yeast pitch rate calculations depend on actual OG. ### Next Batch Prevention * Calibrate and adjust grain mill; test crush visually. * Verify equipment profile in Brewfather is accurate (mash tun dead space, trub loss, boil-off rate) — Brewfather uses these values to calculate expected efficiency. * Perform iodine conversion test at 60 minutes. * Check and correct mash water chemistry (target pH 5.2–5.4). *** ## Playbook 2: Stalled or Stuck Fermentation ### Confirm the Problem * No visible airlock activity for 48+ hours when fermentation appeared incomplete. * Gravity reading same as previous reading taken 24–48 h earlier. * Gravity is significantly above target FG (>5+ points). > **Important:** Always confirm with a gravity reading. Airlock activity alone is not reliable — airlocks can leak or activity can slow while fermentation continues. ### Decision Tree ``` Is the temperature within the yeast's recommended range? → NO (too cold, <15 °C / 59 °F for most ale yeasts): Warm to proper range. → YES: Continue... Was the pitch rate adequate? → Under-pitched: Add a fresh, actively fermenting starter or re-pitch with fresh rehydrated dry yeast. → YES: Continue... Was wort properly oxygenated before pitching? → NO: You cannot fully undo this now; focus on temperature control, gentle rousing, and (if needed) re-pitching healthy yeast. → YES: Continue... Is the gravity stuck near the target FG? → YES (within 2–3 points): Fermentation may be complete; confirm with consistent readings 24 h apart. → NO, well above target: Continue... Is the wort likely low in fermentability (e.g., very high mash temperature, high crystal/dextrin malt load)? → YES: You may be near the practical FG for this wort; verify recipe assumptions before aggressive intervention. → NO: Consider re-pitching with a healthy, beer-appropriate yeast strain with adequate attenuation for the style. ``` ### Immediate Actions (Current Batch) 1. **Warm the fermentation vessel** to the high end of the yeast's recommended temperature range (or a few degrees above). 2. **Gently rouse** the yeast cake by carefully swirling the fermenter — this can re-suspend settled yeast. 3. If stuck after 24–48 h of warming and rousing: re-pitch with fresh, active yeast (starter or properly rehydrated dry yeast) matched to the beer. ### Next Batch Prevention * Calculate and achieve adequate pitch rate (Brewfather's Yeast Calculator tool estimates cells needed based on OG and volume). * Oxygenate wort: \~8–10 ppm DO for ales; \~10–12 ppm for lagers and high-gravity beers. * Control fermentation temperature during first 48–72 h. *** ## Playbook 3: Haze (Unintended) ### Confirm the Problem * Beer is cloudy when clarity was intended. * Haze persists beyond normal cold-crashing time or is not style-appropriate. ### Decision Tree ``` Does haze clear when beer is warmed to room temperature? → YES: Chill haze (reversible protein-polyphenol complex). Cosmetic issue only. → NO: Continue... Was beer cold-crashed (0–4 °C / 32–39 °F) for 48–72 h? → NO: Cold crash first, then reassess. → YES: Continue... Does the beer taste off (tart, musty, medicinal)? → YES: Biological haze (contamination). See Playbook 6 (Contamination). → NO: Continue... Is there visible particulate/floating matter (vs. uniform cloudiness)? → YES: Likely yeast in suspension. Increase cold-crash time or use a fining agent. → NO: Continue... Was Irish moss/Whirlfloc added at the end of the boil? → NO: Lack of kettle finings allows more protein into fermenter. → YES: Continue... Was a whirlpool performed after boil to separate trub? → NO: Large trub carryover contributes to persistent haze. → YES: Protein/tannin haze likely; consider fining agents. ``` ### Types of Haze Summary | Haze Type | Characteristics | Solution | | ------------------- | ------------------------------------ | --------------------------------------------------------------------------- | | **Chill haze** | Clears when warm, returns when cold | Gelatin or silica gel fining; extended cold conditioning | | **Yeast haze** | Uniform cloudiness; yeast-like aroma | Cold crash; gelatin or isinglass fining | | **Protein haze** | Persistent; may be fine/silky | Reduce mash temperature slightly; add Irish moss at boil; cold conditioning | | **Biological haze** | Off-aroma/flavor present | Contamination — see sanitation guidance | | **Starch haze** | Follows incomplete conversion | Confirm conversion with iodine test; extend mash time | ### Fining Agent Quick Reference | Fining | Use Stage | Notes | | ---------------------- | -------------------------- | -------------------------------------------------------------------------------------------------------------------- | | Irish moss / Whirlfloc | Last 15 min of boil | Kettle fining; reduces protein carryover | | Gelatin | Cold-side (fermenter, keg) | Mix 1 tsp in 100 mL warm water; add to cold-crashed beer; 48–72 h | | Isinglass | Cold-side | Attracts yeast cells; effective, fish-derived | | Bentonite | Fermenter | Less common in beer than wine/cider; can strip haze-forming proteins but may also reduce some flavor/aroma intensity | ### Next Batch Prevention * Add Whirlfloc or Irish Moss at 10–15 min before end of boil. * Perform a proper whirlpool rest before transferring. * Cold crash before packaging (Brewfather fermentation step: add a cold crash reading). *** ## Playbook 4: Over-Carbonation ### Confirm the Problem * Bottles gushing on opening; foam fills the glass before liquid; high carbonation in packaged product. > ⚠️ **Safety:** Over-carbonated bottles can explode. If you suspect significant over-carbonation, store bottles in a sealed container (cooler, box) in a cool area. Wear eye protection when opening. Check one bottle: if it gushes, do not serve others until diagnosed. ### Decision Tree ``` Were bottles carbonated with priming sugar? → YES: Continue... Was FG confirmed stable with two readings 24–48 h apart before bottling? → NO: Fermentation was incomplete; residual sugars + priming sugar = over-carbonation. Danger zone. → YES: Continue... Was priming sugar calculated correctly for the target carbonation level? → NO (too much added): Over-carbonation likely. Refrigerate all bottles immediately — cold slows re-fermentation. → YES: Continue... Was equipment sanitary? Could a wild yeast or bacteria have gotten in? → Possible: Biological over-attenuation (wild yeast ferments dextrins). Beer likely tastes off. → NO: Continue... Were bottles conditioned warm (>24 °C / 75 °F)? → YES: Warmer storage accelerates carbonation and can amplify over-carbonation risk if FG or priming was misjudged. ``` ### Immediate Actions (Current Batch) 1. **Refrigerate all bottles immediately.** Cold significantly reduces further fermentation and CO₂ release. 2. Carefully open one cold bottle as a test. Listen for excessive pressure. 3. If pressure is excessive, carefully vent and re-cap bottles one at a time (with eye/hand protection), then keep cold. ### Next Batch Prevention * Always confirm FG is stable (two readings 24–48 h apart) before bottling. * Use Brewfather's **Carbonation Tool** (Tools → Carbonation) to calculate the exact priming sugar weight for your batch volume, desired CO₂ volume, and current beer temperature. * Measure priming sugar by weight, not volume. * Consider kegging for precise pressure carbonation control. *** ## Playbook 5: Under-Carbonation ### Confirm the Problem * Beer pours flat or with very little head; low CO₂ evident. ### Decision Tree ``` Was the correct amount of priming sugar added (confirmed by weight)? → NO: Too little sugar added. Cannot fully correct in-bottle; see below. → YES: Continue... Was conditioning temperature adequate (18–24 °C / 64–75 °F)? → NO (too cold): Move bottles to a warmer location for 1–2 weeks. → YES: Continue... Has sufficient conditioning time elapsed (minimum 2 weeks at 20 °C)? → NO: Continue conditioning. → YES: Continue... Is yeast in suspension likely too low? (Very clear beer, highly flocculant strain, long cold storage before bottling) → YES: For future batches, add a small dose of fresh yeast at bottling. → Continue: Priming sugar may have been under-calculated or unevenly mixed. ``` ### Immediate Actions (Current Batch) * Move bottles to 20–22 °C (68–72 °F) and wait 1–2 more weeks before evaluating. * If still flat after 4 weeks at proper temperature: consider a controlled re-yeast/re-prime procedure bottle-by-bottle with strict sanitation and measured sugar dosing. ### Next Batch Prevention * Use the Brewfather **Carbonation Tool** — input actual beer temperature at time of bottling, batch volume, and target CO₂ volumes for your style. * Ensure at least a small amount of active yeast is present at bottling (do not filter before bottling without adding fresh yeast). *** ## Playbook 6: Oxidation ### Confirm the Problem * Cardboard, papery, stale, or sherry-like notes developing after packaging or over time. * Flavors worsen with age (vs. improving or staying stable). ### Decision Tree ``` When did oxidized flavors appear? → Immediately after kegging/bottling: O₂ pickup during transfer. → Appearing/worsening over weeks: Oxygen ingress via packaging seals or caps. → After dry-hopping: Dry-hop addition introduced O₂. ``` ### Immediate Actions (Current Batch) * Oxidation is largely **irreversible** once present. * Drink the beer young/fresh rather than aging; oxidized beer does not improve. * Evaluate whether the flavor is severe enough to affect enjoyment. ### Next Batch Prevention * **Closed transfers:** Use CO₂ pressure to push beer between vessels rather than gravity/siphon-with-air. * **Purge all vessels** with CO₂ before filling. * Minimize splashing at any point post-fermentation. * For dry hopping: minimize O₂ exposure when adding hops — pre-purge the hop vessel; use a CO₂-purged container or hop spider. * Use oxygen-absorbing bottle caps and properly torque crown caps. *** ## Playbook 7: Hop Harshness / Harsh Bitterness ### Confirm the Problem * Bitterness is harsh, astringent, lingering, or unpleasant rather than clean and balanced. * IBU calculation suggests bitterness should be balanced, but taste says otherwise. ### Decision Tree ``` Is there also astringency (dry, puckering, tea-like sensation)? → YES: Tannin extraction is contributing — see Playbook 1 (mash/sparge temperature and pH). → NO: Continue... Are hops old or of uncertain freshness? → YES: Oxidized alpha acids produce harsher bitterness than fresh iso-alpha acids. → Use Brewfather's Hop Freshness tool to estimate HSI (Hop Storage Index) and alpha acid degradation. Did the beer have minimal or no cold-conditioning? → YES: Conditioning softens perceived bitterness; lager especially requires weeks of cold conditioning. → NO: Continue... Is the water sulfate level very high (>200 ppm SO₄)? → YES: Sulfate accentuates hop dryness and sharpness; reduce for softer bitterness. → NO: Continue... Is the IBU:OG ratio (BU:GU) very high for the style? → YES: Recipe is imbalanced for the style; reduce bittering hop additions or increase OG. → NO: Consider that perceived bitterness is influenced by residual sweetness (FG), attenuation, and water chemistry. ``` ### Immediate Actions (Current Batch) * Extended cold conditioning (weeks to months at 0–4 °C / 32–39 °F) will soften bitterness. * If in fermenter: adding a small amount of gelatin fining can reduce some polyphenol-based harshness. ### Next Batch Prevention * Use fresh hops; store hops vacuum-sealed in a freezer. Use Brewfather's **Hop Freshness Tool** to estimate alpha acid viability. * Adjust water chemistry: for soft, round bitterness, reduce sulfate (< 100–150 ppm); for dry, crisp bitterness, use 150–250 ppm SO₄. * Allow adequate cold conditioning time. * Cohumulone is only one contributor to bitterness quality; prioritize overall hop freshness, recipe balance, and process control over single-metric hop selection. *** ## Playbook 8: Contamination (General) ### Confirm the Problem * Off-flavors: sour, vinegar, musty, medicinal, rope-like, slimy texture. * Visible signs: floating pellicle (film on surface), visible mold, unusual turbidity with off-aroma. ### Decision Tree ``` Is there a visible pellicle (ropey, white/tan film on beer surface)? → YES: Wild yeast (Brettanomyces) or Lactobacillus/Pediococcus contamination. Is the flavor sour/acidic? → Lactic + vinous: Lactobacillus or Pediococcus. → Acetic/vinegar: Acetobacter (requires oxygen; check for O₂ exposure during fermentation). Is the flavor medicinal/band-aid? → Chlorophenols (chlorinated water + phenolics) or wild yeast. Check water treatment. Is there visible mold (colored growth — green, black, pink)? → Mold contamination. Discard the batch. Do not consume. ``` ### Immediate Actions (Current Batch) * **Mold visible:** Discard the batch — molds can produce mycotoxins. * **Bacterial/wild yeast contamination:** Evaluate flavor. Mild lactic sourness may be palatable; acetic/vinegar usually is not. If flavor is objectionable, discard. * **Identify and remove contamination vector before next batch.** ### Contamination Sources * Scratched plastic equipment (replace any scratched fermenters, tubing, or autosiphons) * Inadequate sanitizer contact time or concentration * Residual organic matter (incomplete cleaning before sanitizing) * Airborne contamination (open fermenters near composting material, fruit, etc.) * Untreated chlorinated/chloraminated water (chlorophenol risk) ### Next Batch Prevention * See [Cleaning, Sanitation & Safety](https://docs.brewfather.app/brewing-knowledge/cleaning-sanitation-safety) for full process. * Audit all plastic equipment for scratches; replace suspect items. * Confirm sanitizer concentration and contact time. * Treat water with Campden/metabisulfite at an appropriate dose to remove chlorine/chloramine before brewing. *** ## Quick-Reference Diagnostic Cheat Sheet | Symptom | Most Likely Cause | Quick Check | | -------------------- | ------------------------- | ------------------------------------ | | Low OG | Efficiency loss | Check crush, mash conversion, volume | | Gravity not dropping | Stalled fermentation | Check temp, rouse yeast | | Butter/butterscotch | Diacetyl | Raise temp, diacetyl rest | | Green apple | Acetaldehyde | More conditioning time | | Cooked corn | DMS | Boil uncovered, faster chill | | Solventy/hot | Fusel alcohols | Lower fermentation temp | | Band-aid/medicinal | Chlorophenol / wild yeast | Treat water; check sanitation | | Cardboard/papery | Oxidation | Closed transfers, CO₂ purge | | Sour/acidic | Bacterial contamination | Audit sanitation and equipment | | Gushing bottles | Over-carbonation | Check FG stability, priming calc | | Flat beer | Under-carbonation | Check priming calc, temp, time | | Persistent haze | Protein / yeast | Cold crash, finings, Irish moss | | Harsh bitterness | Old hops, tannins, water | Hop freshness, water chemistry | *** ## Sources * Palmer, J.J. (2017). *How to Brew: Everything You Need to Know to Brew Great Beer Every Time* (4th ed.). Brewers Publications. * White, C. & Zainasheff, J. (2010). *Yeast: The Practical Guide to Beer Fermentation*. Brewers Publications. * Fix, G. (1999). *Principles of Brewing Science* (2nd ed.). Brewers Publications. * Bamforth, C.W. (2003). *Beer: Tap into the Art and Science of Brewing*. Oxford University Press. * Briggs, D.E. et al. (2004). *Brewing: Science and Practice*. Woodhead Publishing. * Daniels, R. (1996). *Designing Great Beers*. Brewers Publications. * American Homebrewers Association (AHA): troubleshooting and sanitation guidance. * Brewers Association: *Draught Beer Quality Manual* (packaging, oxidation, and dispense-related quality risks). ## Related docs * [Quality Control and Off-Flavors](https://docs.brewfather.app/brewing-knowledge/quality-control-and-off-flavors) * [FAQ](https://docs.brewfather.app/faq)