Slow Fermentation

Home brewing can at points, especially when you are starting out seem bewildering. No matter how much you read about something, sometimes you still have unanswered questions. Believe me when I say, “if you have a question about something, it’s probably been asked by pretty much every other home brewer when they were starting out. So what we have here is a frequently asked questions page that will hopefully cover most of the unanswered questions you may have about your first few batches of beer.

This post is constantly updated so when more frequently asked questions arise, they are added.

Table of Contents

The Most Common Worries

So to kick things off I will list what are perhaps the most common concerns of the first time brewer first up it’s:


“Why isn’t my beer fermenting? It’s been xx hours so far!”

This must be one of the most common questions that gets asked when you first start out brewing. It’s understandable really, you have invested the time and money to buy the ingredients and brew the beer and the next part of the process, waiting for it to ferment is one that takes patience. So you pitch your yeast into the wort and you wait but nothing happens that day, you go to bed and get up in the morning, still no activity! Uh, Oh.

Why’s My Beer Not Fermenting!

Unfortunately even the best of us me included sometime can lack patience which is ultimately what it takes. The short answer is this:


Fermentation can take anywhere between 6-8 hours or even up to 72 hours to show any visible signs.

Yes 72 hours, if it hasn’t been that long yet then wait in 95% of cases the fermentation will start after this amount of time. If nothing is happening we can start looking at what’s causing the problem.

No Fermentation Problem Solving

Ok so you have waited 72 hours and there is no visible sign whatsoever of fermentation (if it hasn’t been that long then, wait) what is going on, let start by looking at the simple thing first of all. These are of course the easiest things to solve.

  • Is The Fermenting Vessel Airtight?
    This is the simplest thing to check but it should be the first. If you are looking for signs of fermentation from an airlock bubbling, it’s not going to if the CO2 produced by the fermenting beer is escaping from a poorly fitted lid or a non sealed bucket or bung. Check these first.
  • What Temperature Is The Beer?
    Yeast work in a certain temperature range, if the fermenting vessel is in a room that is cold the yeast will have a hard time doing anything and will hibernate and sink to the bottom. Make sure your beer is sat in a location that the yeast are happiest in. This is usually around 17°C to around 24°C, but check the package to find out. Wait for the beer to warm which could take a day or so and check again.
  • Repitch More Yeast!
    If you have attempted these things to no effect. the next thing to do is to add more yeast. It could be the yeast you originally pitched was no good or that there wasn’t enough viable yeast cells for the quantity or strength of the beer being fermented.

Getting Fermentation Going Quicker

So even though there is no bubbling airlock or frothing krausen it doesn’t mean the yeast aren’t working even still 72 hours is a long time to wait and shortening this lag time should be one of your priorities. When you pitch your yeast they are undergoing certain phases, things like yeast growth rates can be helped along to aid the yeast to do their job, those things we are going to take look at now.

  • Making Sure the Wort Is Aerated
    For yeast to reproduce they need oxygen and that oxygen needs to be present in the beer before it gets pitched. The simplest way to achieve this is to shake, stir and churn it in. Right before you are about to pitch your yeast and the beer is cool and at a good temperature for the yeast to work you need to churn the air into the wort. This can be as simple as pouring the beer carefully from one sanitised vessel to another or even grabbing a sanitised jug and pouring the beer repeatedly from a height. The longer you do this the better a couple of minutes of this and you are getting more of the oxygen the yeast need into the wort.
  • Rehydrate Your Yeast!
    If you use dried brewing yeast then it’s a good idea to rehydrate it before pitching it. Usually there will be instructions on the pack, and if not I shall explain the process below. To ensure a high cell count of healthy yeast we want to rehydrate properly, first of all make sure everything you use is meticulously sanitised, this goes without saying.1. Put around 250 ml of boiled tap water into a sanitised measuring jug and cool to 35°C (95°F)2. Sprinkle your dry yeast onto the surface of the warm water, don’t worry about stirring or aerating or adding sugar. Cover with some aluminum foil and leave it for about 15 minutes.3. Swirl the jar to suspend the yeast, you can stir as well but swirling works just as well and doesn’t involve sanitising a spoon.4. Leave for another 10 minutes. It’s now ready to be pitched into your cooled, aerated wort. To do this swirl the jug to get all the yeast back into suspension and pour the whole lot in.If you are rehydrating your yeast then use it within 30 minutes of rehydrating for the best results.I used to always sprinkle yeast on the surface of the wort and not bother rehydrating but I have changed that now. If I am making a small batch like 3 gallons I generally don’t but for a normal brew length of 5 gallons I always will. Most brewers tend to be meticulous with everything else on brew day so why not take the extra 15 minutes to rehydrate your yeast. What harm can it do given the evidence.
  • Even Better Make A Yeast Starter!
    Whether you use dried yeast or liquid making a starter boosts yeast numbers before they even touch your wort and ensure your beer ferments a lot more healthily. Yeast starters are also important if you are making a higher gravity i.e.higher alcoholic content beer. A guide to making a yeast starter can be found here.

These things will ensure your wort is the ideal solution for the yeast to grow, reproduce and ferment those sugars in and hopefully keep the lag time between pitching to fermentation in a shorter period of time.“My beers are flat, why?”

Flat Beer

This is another pretty common question and most commonly it’s because not enough time has passed between bottling and then opening the bottles. It takes around 3-4 weeks for beers to properly bottle condition and carbonate, if it hasn’t been this long then you need to wait.

Next, is are the bottles too cold. Bottle conditioning with sugar is just the same as fermentation. If the beer is too cold the yeast won’t work so keep the bottles at around room temperature for a week or two.

Another possible cause is the amount of priming sugar you used, if it was too little it’s not going to carbonate very much, check out this carbonation article to find out just how much sugar is needed for your beer.“There is gunk, crusty bits, sludge or generally funny looking stuff floating in the fermenting beer”

Fermentation is pretty disgusting to the outsider or first time brewer, it produces a lot of weird sludge and congealed looking blobs of stuff. 99.9% of the time it’s absolutely normal and is just a consequence of fermentation. Try not to worry and carry on as normal.“Is My Beer Is Infected?”

Lot’s of stuff floats around in beer whilst it’s fermenting and this can raise concerns especially if it’s not familiar to the last beer you brewed, the first thing you should do is jump to the conclusion it’s infected. Oh wait, that is completely wrong, in 99% of instances it’s just naturally occuring crud from normal fermentation. Leave the beer to ferment normally and proceed as normal, it will usually be nothing to worry about.

In fact it’s normally pretty easy to tell if a beer is infected and will most usually be tart or sour when tasted. If you aren’t sure send me a picture and I will have a look for you, or check out this post on how to tell if your beer is infected.“My home brew is ruined, should I pour it down the drain?”

Wait, don’t be so hasty, there is pretty much never any reason to pour away beer unless something has gone drastically wrong. Time heals all things, and this goes for beer. You can do everything wrong when it comes to making beer but leave it be for a period of time and things rectify themselves.

I have brewed a couple of beers that tasted horrible for at least 6 weeks after bottling, heavy beers especially are prone to this. I put these bad tasting bottles away leave them a couple of months and then one day remember I have some. I open them up, try it and lo and behold it tastes great. Make a habit of waiting and considering you’ll be surprised at what can happen with time.

It’s very rare to have a completely unsalvageable beer, even if it’s infected it can still be drinkable, don’t worry about getting sick, it’s next to impossible for pathogens to survive in beer only certain bacteria will survive and the worst that will happen is the beer will taste sour. If you do have an infected beer rack it into a fermenter and leave it for 6 months or so, come back try it, you never know what it’s going to taste like but you may find it’s genuinely nice

Do I Need To Do This?

“Do I need a thermometer?”

Yes! You cannot guess the temperature of the wort, measure it. Those of you that brew beer kits still need to check the temperature of the beer before pitching yeast so go and get one. They are cheap so go and get yourself one!“Do I need a hydrometer?”

Yes! Even if you don’t necessarily care what the alcohol content is of your beer you still need to check the gravity before you bottle to ensure the fermentation is complete. Again get one here! If you aren’t sure exactly how to use a hydrometer all the info you need is here.“Do I need to rack my beer into a secondary fermenting vessel?”

For the most part no you don’t, you can keep the beer in the same fermenting vessel and then bottle or keg it without doing a secondary fermentation. You will get no off flavours or issues with the beer if it’s in the same vessel between 3 – 5 weeks, if it’s staying there longer think about racking it. Doing a secondary however can be useful in certain circumstances, such as brewing high alcohol beers, adding flavourings during fermentation or leaving beer in the fermenter for a long time?“Do I need to wait XX weeks before bottling my beer?”

You should be waiting at the minimum 2-3 weeks before bottling or kegging your beer if you want the best results. Why rush it, the yeast need time to finish up and to flocculate to the bottom of the vessel and you end up with a better beer. Relax and don’t rush things!“Do I need to boil for 60/90 minutes?”

If you are using a recipe that states that yes. The recipe will be formulated for that length of boil. The reason you are boiling for that period of time is to extract the right amount of bitterness from you hops, as well as driving off unpleasant flavour compounds we don’t want in the beer. More information on boiling your wort can be found here – Why You Need To Boil“Do I need to use brown bottles?”

Brown Bottles

Brown bottles are ideal as they protect the beer better than green or clear ones. Whether they are glass or plastic browns best, they stop certain rays of light effecting the hop compounds in the beer and skunking it. Whatever you use, keeping your beer in cool, dark positions is the best practice

Common Off Flavours

If your beer has a certain taste that’s not desirable it may be you have an off flavour that has occurred at some point in the brewing process. These off flavours can range from apple to butterscotch to medicinal.

Here is an in depth guide to off flavours, how and when they occur and some possible solutions to stop them occurring when you brew next.


“Can I boil grain?”

This is another commonly asked question when you first break away from beer kits and start steeping some speciality grains and using malt extract. The answer is ideally no, if you a can remove them before boiling the wort you should. Boiling the grain may extract undesirable compounds and flavours. If there is a small amount of grain left in solution though it shouldn’t be a big problem. I have done this myself when I first started brewing, check out this account of the incident here.“Is liquid yeast better than dry yeast?”

In short no, not really. A beer made with dry yeast tastes just as nice as a beer made with liquid yeast. The real benefits of using liquid yeasts however is the sheer variety of strains available. You can make styles of beer that you can’t really replicate with the available strains of the dry stuff. That being said though I would guess around 75% of my beers are fermented with dry yeast.“How should I store leftover brewing ingredients?”

The main thing to bear in mind for storing grain over any period of time is too keep it dry, because of the way it’s manufactured and processed via kilning malt usually contains around 4 – 8% moisture. Over time if the crushed malt (this is how it’s usually sold in the UK) is left exposed it will start to absorb moisture from the air and it obviously a lot more likely to spoil and deteriorate.

Storing Malt

If you are anything like me then after a little while of brewing you will end up with a whole box full of malt and other grains that have been used in other recipes and now reside half used until you buy another bag of the same stuff because you forgot you had some.

Storing malt is a question I see being asked a lot in home brew forums around the web, I have done a bit of research on it myself so wanted to address it here.

When you start brewing you will inevitably accumulate different types of malt, grains and adjuncts, you will use these in whatever recipe you purchased them for then the remainder needs to be store. All-grain home brewers especially are often buying grains in quantities of up to 25kg so making sure this malt is in the best condition, ready for your next home brew is vital to consistently make good beer.

The easiest way to store malt is too keep it sealed and limit the exposure to the air. You can buy air tight containers or ziplock freezer bags for this purpose and they will easily ensure the longevity of your stored malt. I myself have a bag sealer which allows easy resealing of the bags the malt are supplied in by the home brew retailers, as soon as I’m done weighing the quantity required for whichever beer I’m brewing, I can reseal the bag.

Trying to keep the malt in a cool, dark place seems to be the general preference for most brewers to store the left over grain. In a cupboard or something similar should be fine.

Like any raw ingredient the fresher you use it the better your resulting home brew will be, however storing malt in this way I have used small quantities of seldom used grains, up to 12 months after purchase.

Hops need to be stored cold and sealed if possible, a more in depth guide to hop storage is here. As for storing you home brewed beer check out this article for how long home brew lasts.

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  1. Paul KamulskiPaul Kamulskisays:can I brew a lager from an ale kit if I use a lager yeast?Reply
    • NeilNeilsays:You could do this, it is most likely not going to end up like a crisp Pilsner type lager but rather a more malt led lager similar to beer styles like Vienna Lager.You will probably want to ferment at lower temperatures and for longer according to the lager strain you are using.Reply
  2. Brandon KisnerBrandon Kisnersays:I was doing some spring cleaning and found a case of beer I had brewed a couple years ago that I had forgot about due to us moving and I being put in the back of the closet. I popped open one and it is still carbonated and doesn’t smell bad. In fact it smells like the alcohol content has gone up. Do you think it is safe to drink?Reply
    • NeilNeilsays:Pathogenic bacteria cannot survive in the low pH and alcoholic environment in beer so it won’t make you ill. Beer can still sour and taste unpleasant but these kinds of bacteria aren’t harmful so as long as it tastes ok it is safe to drink.Reply
  3. DannyDannysays:Hi, just wondering about the carbonation article you mentioned under the question about flat beer. I can’t find the link to the article. (What I’m really wondering is, do you have to use more priming sugar at bottling if you have done a secondary fermentation, as opposed to bottling right from the primary? Ever since I’ve started racking my beer kits for a secondary fermentation, my beer has been flatter.)Thanks!Reply
    • NeilNeilsays:As long as fermentation is completely finished it shouldn’t make a difference. I would say it is most likely to be a temperature related difference, the cooler a beer is the more residual carbonation it will have. It may be that the beer in secondary is slightly warmer. Check this calculator for a way to work out the difference –
      • RaymondRaymondsays:I please need urgent assistance. I’m attempting my first apple beer.
        What happens if I used too much yeast? And how to I balance my beer out, if I used to much yeast?Reply
  4. stewartstewartsays:How long can you keep elderflower wine?Reply
    • NeilNeilsays:Elderflower wine will last for a few years if not more. I find my Elderflower wine is best after a year and peaks after 2 or 3 years.Reply
  5. JakeJakesays:Pretty sure I added the priming sugar to the wort of an IPA. No idea why. Ready to bottle soon. What should I expect or do to salvage this beer?Reply
    • NeilNeilsays:Sorry for the late reply. It is not a big problem, the priming sugar you added will boost the ABV a small amount but not by much. It will just be fermented out with the rest f the beer. When you bottle the beer you will just need to add more priming sugar then.Reply
  6. Srinivas MazumdarSrinivas Mazumdarsays:I want to know if I can dilute my batch after I have added yeast and fermentation has started ? I miscalculated the water required when I made the batch.
    Or can I dilute at bottling stage ?Reply
    • NeilNeilsays:You can but I would only use boiled and cooled water. It is not ideal but if there is no other way around it this is what I would do.Reply
  7. MatthewMatthewsays:I am doing a brew and after fermentation it is telling me to do a diacetyl rest for 6 days. What is this and is there anything special I need to do. Do I remove the airlocks to do this.Reply
    • NeilNeilsays:Diacetyl is a byproduct of fermentation that leaves a strong buttery taste that is not desirable in the beer. A diacetyl rest is usually part of the process of brewing lagers or other light beers, all you have to do is leave the beer in the fermenter at a temperature of around 18-20C (65-68F). This rest at this temperature allows the yeast to clear up any diacetyl from the fermentation.Hope this helps
  8. RodRodsays:I put down a small batch of pale ale and had fermentation for 4 days but noticed I have no yeast activity going on it just dropped and not much more is happeningno or next to nothing yeast activityReply
    • NeilNeilsays:Hi Rod,I would suggest taking a hydrometer reading to work out how far fermentation has progressed. If you haven’t got a hydrometer then taste a sample to see if there is still sweetness left.You may find the yeast drops after this short period as the majority of the sugars have been fermented already. This does not mean they have stopped all activity, however, they will still be working to remove byproducts from fermentation so the beer still needs to condition on the yeast.Hope this helps, if you need any more info just let me know.Reply
  9. MarkMarksays:I am brewing a high alcohol Stout, it started at 1.125 SG,did fermented like heck for a week, then stopped at SG 1 .070. I already did the following, I pitched more ale yeast, waited 10 days nothing. I pitched more champagne yeast, and stirred it daily, waited 10 days, nothing, I brought it from my kitchen to my garage which increase the temperature by 10° so now it’s sitting at 80 degrees, The SG went to 1.065 over one week. I have made this recipe seven or eight times over the last 15 years, this is the first time that I’m using a conical fermenter oh, that we don’t really think that that’s the issue. The only other difference between this recipe in the other ones that went find is I added agave syrup in the boil. … The beer still smells like beer… Any ideas about what to do here?Reply
    • NeilNeilsays:Hi Mark,Admittedly it is a high FG and it sounds like you have done the right things so far. Is it an all grain beer, if so what was the mash temp.I am interested to hear more about the agave syrup, I have not used Agave syrup before but it appears to be simple sugars which should be highly fermentable. It may be worth checking the syrup container to ensure that there is no additives or artificial sweeteners added.Reply
  10. Jim stegerJim stegersays:Can you use a lager yeast in a red ale mix or vice versa what is the result what changes.. Does it affect the flavor and alcohol content and what about fermentation time?? I accidentally did this ordered two batches at once and mixed up the wye yeastsReply
    • NeilNeilsays:Yes, you can, it will impart different qualities but will still work. It is important to ferment in the range for the yeast you are using and lager yeast typically require lower temperatures. The ideal range will be listed on the package.Reply
  11. Chris SoboleskiChris Soboleskisays:Will be bottling in one-liter bottles. How many carbonation drops per bottle at approximately 3.0 grams per each drop? Thank you.Reply
  12. KyleKylesays:A friend just bottled 12oz of beer in a 22oz bomber for conditioning (it was all he had left of each at the end of the process).
    Everything I read states the additional oxygen inside the bottle would hurt the beer via oxidation… that respiration of yeast won’t occur with sugars available (just fermentation), the added room up top will cause less concentration of CO2 to infiltrate the liquid, yadda yadda yadda.
    He opened that half filled 22oz bottle after 4 days and had a beautifully carbonated drink. How could this be??Reply
    • NeilNeilsays:It’s difficult to say. The beer will carbonate as the CO2 has nowhere to go. Was the rest of the batch carbonated in the same way?4 days is a very short amount of time to get carbonation without using agitation to force CO2 into the beer.Reply
  13. brettbrettsays:have a question
    what happens to your brew if you have added the carbonated drops into the fermentation processReply
    • NeilNeilsays:Hi Brett, the carbonation drops will ferment out during primary fermentation and increase the ABV slightly. You will need to add more sugar to carbonate prior to bottling.Reply

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