FAQ for Beer Brewers

Hints and tips to solve common brewing issues


Q.  How long should my beer ferment?

A.  Actually it’s not about time, it’s about when has the yeast finished their job of fermentation. In beer making, all time is relative to temperature. If you've used the little white pack of generic brewers yeast, the warmer the brew, the faster the ferment, reducing quality and the quicker it will spoil once fermentation has finished, that is, prior to bottling. Try to aim to ferment with this yeast between 18 & 22° C The cooler the brew, the more slowly things happen and the lower the off flavour production. Learn to use your hydrometer / refractometer to be sure when to bottle, having 3 days with a stable reading is the only sure way to tell when to bottle, this confirms all available sugars have been used by the yeast. The fermentation stage is a most critical time in brewing for achieving best results so take care here.

Brewers who are chasing better quality results will swapout the generic yeast satchel and replace it with a larger pack of yeast that will give far superior results if brewed n the right temperature range.  Ale temperature range 16°-22°C - Lagers generally 8-13°C, followed by what is known as a Diacetyl Rest (2-3 days at 18°C).  It’s not a race.... Don’t be in a hurry and you will make far better beers!


Q.  Why use a different yeast

A.  More than half of the flavours that we perceive in beer are yeast derived or related. Pitching the wrong yeast will not enable you to achieve the full potential in each brew. Lager beers need lager yeast, and ales need ale yeast. Many beer styles are historically associated with certain yeast strains and it's the yeast strains that contribute the greatest proportion of the flavours that make that style of beer what it is.

To determine how much yeast to use for a particular style, we suggest you go to the exceptional Yeast Pitch Rate Calculator located at:  PITCH RATE CALCULATOR (Click Here)


Q. Air-lock not bubbling

A.  This is the most common “problem” of all. Usually the individual assumes the brew is not fermenting so “Out she goes”. Fermenters do not always seal well and if not sealed, the air lock doesn’t bubble (old seals are a common cause of leaks). First, assess the situation properly by taking a hydrometer reading or by looking for visual signs of what’s going on. If the brew is still fermenting, seal it as well as you can, get a new lid/ seal/ grommet before you next brew. If it is finished, bottle immediately. Don’t throw it out, as it’s quite possibly OK. The airlock is there to keep insects and air out, allow CO2 out and it is not as a guide to fermentation activity.


Q.  Fermentation doesn’t start or stops early

A.  Genuine lack of fermentation can only be caused by:

  1. Not adding the yeast or the sachet is old and inactive.
  2. Adding yeast to a wort over 37°C
  3. Temperature too cold, below 16°C can cause definite problems for ale yeast (supplied with many home brew beer kits). Warm the brew gently by using a brew heater or some other method to 18-22°C. Brews will often stop in the later stages of fermentation in cold conditions. Better still, at low temperatures, switch to proper lager yeast.

However 99 times out of 100 it will be simply poor sealing of your fermenter.  Don’t trust the airlock to tell you what's going on !


Q. Can I add another yeast?

A.  Many home brewers add another yeast because they think the brew is not fermenting. Often the fermenter has simply not sealed or fermentation is already finished. The lag Phase for yeast growth can be 24-48 or more hours. The anxious brewers gaze at the air-lock and if it’s not bubbling, they assume nothing is happening. Relax ! Have a home brew and take a deep breath. Fermentation is inevitable if the temperature is right, (however it may not be the yeast strain we were hoping for!) so use your hydrometer if there’s any doubt. Don’t rely on the airlock  - that’s not what it’s there for! ALWAYS do a hydrometer reading before pitching the yeast. If a second hydrometer reading shows a lower gravity, then the beer IS fermenting. (See also Q. Air-lock not bubbling, above).


Q.  Frothing through the air-lock

A.  This is a common problem in hot summer conditions. Absolutely no harm befalls the brew; it only happens in the first stage of fermentation (called the Krausen – it could actually  be a good sign if the temperature is in the correct range 18-22 for ales around 12 for lagers). Simply wash the air-lock and refill it with water and a touch of sanitiser. Alternatively ask staff how to fit a blow off/overflow bottle.


Q.  Mysterious hydrometer readings

A.  While a beer hydrometer can be used to monitor the progress of fermentation; most home brewers have definite problems in getting accurate readings. Where there is any doubt as to which reading is the correct one, take the lowest reading or in other words, that closest to 1,000 as the accurate one. Before taking a reading, spin the hydrometer a couple of times in the liquid to remove bubbles.


Q.  Bubbling won’t stop

A.  Slow air-lock bubbling can continue for an extended period of time in the perfectly sealed fermenter. It can be caused by air expansion as the room warms and then reverse bubbling can occur as the room cools. This will eventually lead to oxidisation of your beer.  Ascertain the correct time at which to bottle by using your hydrometer or Refractometer. Don’t use the air-lock to determine when to do anything! Home brewers often leave the brew in the fermenter too long because of slow air-lock bubbling (not always a sign of fermentation) or bottle too early and over gas – even leading to exploding bottles. Brews can spoil fairly quickly if not bottled at the correct time without temperature control, especially if fermented in a hot garden shed etc...


Q.  What’s with the Sediment in the bottle?

A.  As most commercial beer contains no sediment in the bottles (increasingly, many do – often very good ones at that), some new home brewers can  become obsessed with achieving the same with their brews. There is always small final sediment in the bottles of home brewed (bottle conditioned) beer from the secondary fermentation that takes place in the bottle for carbonation. If the beer is made correctly, the sediment should be similar to a coat of paint on the bottom of each bottle. The behaviour of the sediment is yeast strain dependant and they are graded as high, medium and low sedimenters.  The answer is compromise and understanding. Allowing your brew short but sufficient time to settle before bottling and the use of finings is also a way to reduce sediment in beer.


Q.  Which sugar for the bottles?

A.  Carbonation drops make this task easy; two per tallie, 1 per stubby. Alternatives are white sugar, Dextrose, Light dry malt or even honey - dosage rates vary greatly.

Ask staff for a handout on bulk priming or go to our easy guide to bulk priming on the website.  Essentially, this is a way of distributing a priming malt (or similar) throughout the entire batch of beer and then bottling it. It’s a bit more work, but is a popular way to prime bottles.


Q.  My bottles are exploding

A.  This condition can only be caused by excess sugars in the bottles after capping. You can create excess sugars in two ways.

  1. Most commonly:  You may have bottled too early, when there were still unfermented sugars in the brew. The remaining unfermented sugars in addition to your priming sugar will in time over gas the bottles. Monitor your fermentation temperature and determine when to bottle using your hydrometer or refractometer (2-3 days constant reading ie. 1.012) not airlock activity.
  2. You may have added too much sugar to each bottle. Some people are of the opinion that if one teaspoon to each bottle makes a good brew then three teaspoonfuls will make it even better – NOT SO. Crazily, some still believe that the alcohol content of the finished beer depends on the sugar you add to each bottle! You may have primed a bottle twice with sugar. It’s easy to do – If the odd bottle is inconsistent with the rest of the batch, you have doubled up. Use carbonation drops they are a measured dose and easy to count, if you lose track, most of us can count to 2 J. To achieve different carbonation levels or to bottle into odd size bottles check out my handout on bulk priming.

Some rare exceptions are caused by brettanomyces yeast or wild yeast infection, causing slow degradation of dextrins usually in high gravity dark beers and lambics.


Q.  Over-gassed beer

A.  Same as above but not as bad.  Certain bottles or even whole batches of your beer may at times become over gassed, while not necessarily exploding. This condition is also caused by one of the above mentioned reasons. Bottles that almost fill the glass or jug with froth may be brought under control by chilling the bottles to close to freezing point for a few days prior to opening.


Q. Flat beer – little or no gassing

A.  True flat beer can be caused by the following factors:

  1. Insufficient or no priming sugar in bottles when bottling.
  2. Bottles not sealed properly.  The capper bell may have stretched - it happens!
  3. Very cold carbonation / maturing conditions (can cause insufficient yeast activity)
  4. Insufficient time in the fridge before serving. Allow 2-3 days chilling. The colder the liquid, the more gas is absorbed AFTER carbonation.
  5. Highly flocculent yeasts may not have had a high enough cell count if the beer is transferred to the bottles long after primary fermentation has finished.


Q.  Poor head

A.  If a beer refuses to form and then hold a good head, chances are the beer is either under-gassed or insufficiently matured. Poor head is also common with cheaper beer kits due to lack of malt protein in the mix, or the addition of significant quantities of cane sugar, don’t be a tight wad, get a better beer kit, we are talking about a few cents a glass here, not sheep stations.  If the bottle has not been refrigerated for at least 3 days prior to opening, gas will not have had time to absorb into it and escapes with the cap. Kit Brewers, could use “Big head powder” or up to 250g of maltodextrin if the problem persists. Bottle carbonation can take several weeks - It takes a good deal longer to bottle-mature a beer. Allow a Minimum of 2-3 weeks for carbonation and a further 4-6 weeks for conditioning. Most knowing brewers bottle conditioned beers for at least 12 weeks, and they can be better at 12 – 18 months if stored correctly some Stouts and dark beers are exceptional at 3-4 years old. Most home brewers drink their beers long before they are at their best. Try putting a few aside from each batch to age longer and you will soon have a stock of well aged beer. Once you see the difference you will want to age all of your beers. Glass cleaning also has a lot to do here, don’t use soapy detergents on glasses - it kills head if not properly rinsed. Dishwashers also kill beer foam especially the rinse aid. Use your brewing detergent, scrub thoroughly and rinse with boiling water, don’t dry unless you have a clean glass cloth, air dry on a rack or put them straight in the fridge. Nucleated glasses are a big help.


Q. What are these “Off” flavours

A.  Most often caused by too high a fermentation temperature/ poor hygeine. Yeast prefers a temperature much higher than the temperature at which good beer is made – You can choose whether to make the yeast happy or make good beers – go for the quality brew result every time.  I drink beer not yeast! Some off flavours in a finished beer are the result of contamination. This could be caused by the water you’ve used in the brew, poor hygiene or exposure to contaminants late in fermentation, or during bottling; If only the odd bottle tastes “off” then the problem is with your bottle hygiene or splashing during bottling. Should the whole batch taste crook, pay more attention to your method of brewing (temperature) and sanitizing next time. For instance, a common contamination often comes at the end of fermentation. That is if you were to open your drum very late, then reseal it and leave for a few days prior to bottling, chances are there will be a white film on the surface of the brew when you go to bottle. This form of contamination can also appear in the bottles. It won’t do much for the flavour of the beer. Bottle as soon as possible after fermentation finishes. Bottle in brown glass or PET bottles, Light can affect beer in a matter of even 5-6 minutes,  the result is called “skunked “beer because it tastes so bad A.K.A. Light struck beer. It is caused by near UV wavelengths of light interacting with sulphur compounds from hops. Because of this reason don’t bottle in direct sunlight!

There are several chemical compounds that produce particularly noticeable “off” flavours. These include:

Acetaldehyde: Has a green apple /cider/funny bitter flavour. It’s a common problem with beers which have been rushed through the primary fermentation phase, bottled early or when they’re made using straight dextrose/high dextrose blends. Acetaldehyde is a precursor to the formation of ethanol. In most cases, it will decrease and even disappear with time. (time heals nearly all in brewing)

Other causes of Acetaldehyde in beer include:

  • Insufficient aeration/oxygenation of the wort before pitching yeast
  • Pitching insufficient east – 5 or 7 grams just doesn’t cut it.
  • Pitching yeast at elevated temperatures ie keep it under 24 Degrees C
  • High primary fermentation temperature. (Read Article on temperature Controlled Fermentation) Do you think commercial breweries brew on a benchtop in the warmest place available? Nope.

The best solution to this is to follow these simple steps:

  1. Use good quality beer kits.
  2. Use a mainly malt in your blend  (i.e. all malt/Malt Maltodextrin/or Ultra Blends)
  3. Allow 2-3 weeks for carbonation and then allow your beers to age for a minimum of 6-8 weeks before consumption (EXCEPTION: Most Wheat Beers are good to go after 2 weeks of carbonation time)
  4. Aerate the wort well. The yeast needs plenty of oxygen in the first 24 hrs of fermentation
  5. Pitch enough yeast of the right type at the right temperature

DMS: Has a distinctive of sulphur or cabbage like flavour. The most likely cause in kit beers is bacterial infection, but cross infection with wild yeasts or cross contamination from distilling yeasts can also cause similar sulphury tastes.

Diacetyl: Is a by-product of yeast activity in the primary fermentation phase.  In Lagers, it is an unwanted compound that spoils the flavours. Diacetyl tastes “buttery” or “butterscotch like”. While it adds to the complexity of flavours in some styles of Ale at very low levels, it’s dreadful in Lagers.  When diacetyl builds up in a lager during cool fermentation, allowing the brew to warm up gradually at the very end of the primary fermentation stage by a few degrees for 48 hours will allow the yeast to consume the diacetyl, removing it completely. This process is called a “diacetyl rest”. The process involves gently bumping up the temperature of the beer to around 18° C.


Q. I have Hazy beer

A.  Most home brews will take a week or so to clear after bottling, but should then settle out (except some wheat beers). If your beer refuses to clear after a reasonable time, ten to one it’s affected by one of the following problems:

  1. Oxidization – This is caused by excessive exposure to oxygen during bottling.
  2. Starch haze - This means a hazy state created by the addition of starchy additives to the brew.
  3. Chill haze – Occasionally when a beer is chilled. It may become slightly hazy. This condition can occur with any beer. It is can be caused by a slightly higher than normal protein content in the basic ingredients. The beer is perfectly all right. There is no effect on taste, as it is a natural occurrence, save these ones for black outs. By the way, haze is quite common and natural in wheat beers. Polyclar VT added to brews prior to filtering will remove most hazes from beer!


Q. Diet and diabetic beer

A.  Both “diet” and ”diabetic” beer are really the same and should not be categorised with low alcohol beers. Low alcohol beers are basically normal beers with a reduced alcohol percentage. In home brewing, we assume that the fermentation (both primary and secondary) ferments all the sugars available; however, the yeast cells usually leave a small percentage just as you don’t eat all the crumbs on your plate. Home brewed beers will always contain some quantities of unfermented sugars: however, many diabetics report that well matured home brews give them fewer problems than normal (non-diabetic) commercial beers. Try adding Dry Enzymes to reduce starches.

In reality, there is no such thing as a true Diabetic Beer.  Essentially, diabetics should only drink light/low alcohol beer and the effect of dry enzymes pitched at the same time as the yeast will help just a little. Moderation is the key.

Grain brewers note: The closest thing you'll probably find to a near-zero carb beer will come from grain brewing with malt like Australian Galaxy malt, mashed at low temperatures for extended times. Done up with low IBU's (6-12) and a late kettle additon of hops, it can be super light, dry body and quite enjoyable on a hot summer afternoon.


Better Beers Summary:

Clean and sanitise thoroughly.

Use quality Kits.

Use quality additions in you beer: MALT where possible, avoid high loads of simple sugars such as table sugar or dextrose.

Temperature controlled fermentation (ie. fridge and temperature controller) will yield consistent and good to excellent results.

Use finings for a clearer beer.

Age/Condition your beer.

Knowing brewers produce their beers early and age/condition their beers for months before enjoying them.