Fermentation "rate" fluctuating

[chabuhi]

Hi everyone -

HBT (and homebrew) newbie here - actually that's not totally true - I did the Mr. Beer thing ... 20 years ago? (wow) when it first came out. And it sucked (my fault, no doubt).

Anyway, my sister and brother-in-law got me an extract kit from one of the many online HB kit sellers. I boiled it up and started fermentation this past Saturday (two days ago). The bubbles began very slowly (about one per every second or two) on Day 2, and by the end of Day 2 were up to about 2 or 3 per second.

Today (Day 3) I checked on the bubbles and noticed that they have slowed to 1 every 2 or 3 seconds.

I realize it's very early in this stage, so is it normal for the bubbling to "rollercoaster" like that? Should I expect it to pick up again? Or has my yeast spent itself far more quickly than it should?

Just to note, I was very meticulous about following the instructions, sanitizing, temperatures, timing, etc.

Here's where I was NOT so meticulous:

1. The one-gallon boil yielded about two quarts of wort (maybe that's normal, I don't know). The instructions said "add water to just below the 1 gallon mark on the carboy if necessary" - well, boy was it necessary. I had to fill most of the carboy with filtered water to get to just below the gallon mark. I've since read that I should try to get a taller, more narrow boil kettle to limit boil off.

2. After pouring the wort through the fine-mesh strainer (too fine, imo, took forever to strain through just 2 quarts of wort) I shook up the concoction per the instructions and set up the blow-off tube. A minute or two later is when I discovered the unopened yeast packet on the counter. So I carefully removed the stopper and added 1/3 of the yeast packet (per instructions) and shook it all up again.

Again, I'm sure there was ample opportunity for contamination, though I was very careful in handling everything and not touching any of the sanitized parts that would touch the wort (or touch them to anything that wasn't sanitized). To be honest, in my admittedly amateur opinion if contamination occurred then brewing beer is not something that should be attempted outside of a BSL-4 hot lab at USAMRIID or the CDC. Just sayin'.

Anyway - appreciate any feedback from you all. I searched the forums and did not find anything specific to "bubble rate". So if this has been asked to death already, I apologize, but I promise I did try to search first.

Thanks for any insights!

- Chip

 

[masscarriers]

It's fairly possible most of your fermentation is already done by now, you should definitely expect to see less bubbling going forward. Nothing strange here.

 

[peterj]

That sounds completely normal. When you first add the yeast they begin what's called the lag phase where they are rapidly reproducing to a level that is large enough to consume the fermentable sugars in the wort. You won't see much activity (krausen, airlock, etc.) during this phase which will usually last from 8-36 hours. Then as the population rises they start fermenting more and more of the sugar during the active fermentation phase. This is when you will see a lot of churning, krausen, and (if you have a good seal) lots of airlock bubbles. This should last somewhere between 3-5 days. It will rise, then peak, then start to decline. During the rest of the time (maybe another week or week and a half) the krausen will sink back into the beer and you won't see much airlock activity. The yeast are slowly eating the last remaining sugars, cleaning up some of the by products of the aggressive fermentation, going dormant, and settling out to the bottom.

If your fermentation temperature is too warm, then all of this will happen faster and you could get some off flavors and possibly fusel alcohols which can cause headaches and hot alcohol flavors.

What temperature is your beer fermenting at and what yeast are you using?

Also, topping up with water is ok but if you know about what you're going to boil off it would be better to start with more water and boil down to the correct amount. So if you boil off 0.5 gallons per hour you can start with 1.5 gallons in your pot and then you should have 1 gallon after the boil.

And you don't have to shake the yeast in. The shaking is to aerate the wort to give the yeast oxygen for their initial reproduction. After fermentation begins though you want to limit the oxygen exposure. It's best to rehydrate dry yeast, but either way you can just pour it in and it will get to work. Shaking won't hurt it though so don't worry about that.

Sounds like you should be fine as far as contamination goes. As long as you're aware of it and you try to keep everything sanitized, I think the beer will be fine.

 

[ncbrewer]

Welcome to HBT and good luck.

 

[chabuhi]

Thanks, all, for the replies and the warm welcome!

@peterj - thank you for that detailed info - much appreciated!

To answer your questions (I guess you really only had one):

The room (basement room) the beer is fermenting in is 70 degrees pretty consistently. Not sure if you meant the room temp or the temp of the beer ... the beer temp I don't know.

Shaking the yeast in was a mistake on my part. The directions clearly said to shake the wort and then add the yeast. I guess I got mixed up after forgetting the yeast and absent-mindedly shook it in. Munton's(?) yeast was what came with the kit.

Great point about starting with more water. I guess a good portion of this is going to be trial and error, so I suppose I should just be happy if I don't die after drinking my first batch!

Thanks again for the help and I just want to say that HBT has a really cool group of participants. I was searching the forums probably every minute while brewing my first batch and have to say this is one of the finer online communities I've been involved in. Officially joined today and looking forward to my member decals!

 

[peterj]

No problem!

And there's nothing wrong with aerating right after pitching the yeast, it's just usually the last thing people do. At least for me I feel like once I pitch the yeast I seal up the fermenter and that's it!

Also, for future batches I would try to keep them cooler than that. The beer temp can be about 5-10 degrees hotter than the ambient temperature so if it was 70 in the room then the beer was probably somewhere north of 75F during the height of fermentation. Depending on the yeast you used you might be getting some off flavors and possibly some hot fusel alcohol production.

For most yeasts you generally want to keep the beer temperature no higher than 68-70F. I usually shoot for 65 and try to keep it at least under 68. Every yeast has specific temperature ranges though. A good way to do this is to put the fermenter in a big tub of water. Then keep a thermometer in the water and switch out frozen water bottles to keep it at the right temp. I usually switch them about 2-3 times a day. And the temperature is really only critical during the first few days of lag time and vigorous fermentation. That is when most all of the potential off flavors are going to be produced. So once it starts slowing down you can let the temperature creep up if you want.

 

[chabuhi]

Great - thanks, Peter! I actually have the carboy and blow-off assembly in an empty 20qt kettle as I was concerned about a possible overflow if fermentation went crazy. I can just add cool water to that and monitor. Although, after last night's bat**** crazy storms here the temperature is down a few degrees, so I might hold off on cooling the carboy further for now.

One more question (probably not): Am I good to switch out the blow-off assembly for the air-lock at this point? Or should I still wait a couple more days? Thanks!

 

[peterj]

If things are starting to slow down and it hasn't needed the blow off yet, you're probably good to switch it out now.

 

[chabuhi]

Well, I'm 72+ hours in and fermentation appears to have stopped completely since early into day 2 (if not sooner). I switched the blow-off tube for the air-lock, and at peterj's suggestion I put the carboy in a tub to try to keep it between 68-70F.

From what I have read, the lack of bubbles is not a sure sign that fermentation has stopped or isn't happening, but I don't know how else to tell other than a brewing hydrometer (and I'm not sharing my salt-water hydro). I certainly don't want to wait a month or more to find out that the yeast died off too soon. The kit instructions said to add about a third of the yeast and discard the rest. Maybe I didn't add enough?

One thing I'm wondering is if it makes more sense for beginners to start with a larger batch than the typical 1-gallon kit? I'm just thinking from an aquarist's point of view where beginners almost always make the mistake of starting with a 10-12 gallon fish tank thinking that it makes sense to start small. However, it is much more difficult to maintain a healthy water environment in small tanks than larger tanks. Temperature fluctuations occur very rapidly in small volumes of water, for example. I figure the same applies to brewing beer, so I wonder if beginners would be better off doing a 5-gallon batch.

I don't know, I'm sure I'm overthinking things as always.

 

[Yooper]

Well, I'm 72+ hours in and fermentation appears to have stopped completely since early into day 2 (if not sooner). I switched the blow-off tube for the air-lock, and at peterj's suggestion I put the carboy in a tub to try to keep it between 68-70F.

From what I have read, the lack of bubbles is not a sure sign that fermentation has stopped or isn't happening, but I don't know how else to tell other than a brewing hydrometer (and I'm not sharing my salt-water hydro). I certainly don't want to wait a month or more to find out that the yeast died off too soon. The kit instructions said to add about a third of the yeast and discard the rest. Maybe I didn't add enough?

One thing I'm wondering is if it makes more sense for beginners to start with a larger batch than the typical 1-gallon kit? I'm just thinking from an aquarist's point of view where beginners almost always make the mistake of starting with a 10-12 gallon fish tank thinking that it makes sense to start small. However, it is much more difficult to maintain a healthy water environment in small tanks than larger tanks. Temperature fluctuations occur very rapidly in small volumes of water, for example. I figure the same applies to brewing beer, so I wonder if beginners would be better off doing a 5-gallon batch.

I don't know, I'm sure I'm overthinking things as always.

It sounds perfectly fine! You can wait a week or so, and then check the SG and then check it again three days later and proceed to bottling if it's the same (and it should be certainly by then).

I know many people are restricted by their ability to boil and cool 5+ gallons of wort, so for them 1- 2.5 gallon sized batches make sense. Since bigger batches are no more work, and I always had a great stove and a chiller to chill wort, I almost always did a 5 gallon batch or bigger. It really depends on the person. Some are content with 1 gallon sized batches forever.

 

[peterj]

Yeah it sounds fine to me too. You pitched enough yeast, I think it's just done with the bulk of fermentation. You should get a hydrometer to measure the gravity (they're pretty cheap on amazon or at an LHBS).

It sounds perfectly fine! You can wait a week or so, and then check the SG and then check it again three days later and proceed to bottling if it's the same (and it should be certainly by then).

Do this and you should be just fine!

 

[chabuhi]

Thanks, Yooper! That sets my mind more at ease. I may stick with one-gallon kits for now until I get the process down. Opinions may differ, but throwing out beer is not as big a deal as throwing out dead fish (gasp! how dare he say that!). Plus, you bring up a good point - I'm not sure how well our stove will handle a full 20-qt pot. May need to graduate to a stand-alone burner ... which means boiling outdoors so I don't accidentally kill my family. Good thing winters around Chicago are so mild.

Edit: Thanks also, peterj! (Sorry, your reply dropped to page 2 so I didn't see it at first.) I guess the whole AP chemistry lab blow-off contraption had me expecting a more aggressive reaction. Just not knowing what to expect is part of the challenge, I guess.

 

[balrog]

I may stick with one-gallon kits for now until I get the process down...I'm not sure how well our stove will handle a full 20-qt pot. May need to graduate to a stand-alone burner

There is also "partial boil" method, if you don't want to go full 8G pot, requiring wort chiller. You just boil 2-3G or so, which can still be cooled with stew pot boil kettle floating in sink changing cool or iced water out.

 

[chabuhi]

Thanks, balrog - the sink is not very deep, but the pot does fit in it ... maybe twice as tall as the sink? Anyway, something to keep in mind, thanks!

Another question to everyone - there is quite a bit of (what I assume is) colonized yeast clinging to the top of the carboy. I don't believe it is blocking the airlock (it wasn't blocking the blow off tube when I removed it), but I was just wondering if I should knock/shake it down into the wort? Doesn't seem to me it can be eating much sugar if it's not IN the sugar?

 

[peterj]

Thanks, balrog - the sink is not very deep, but the pot does fit in it ... maybe twice as tall as the sink? Anyway, something to keep in mind, thanks!

Another question to everyone - there is quite a bit of (what I assume is) colonized yeast clinging to the top of the carboy. I don't believe it is blocking the airlock (it wasn't blocking the blow off tube when I removed it), but I was just wondering if I should knock/shake it down into the wort? Doesn't seem to me it can be eating much sugar if it's not IN the sugar?

No it's fine, you should leave it alone. There is plenty of yeast still in the beer. And that's not all yeast on the side, it's the remnants of the krausen which is made up of yeast, proteins, hop particles, etc.

 

[balrog]

+1 on Leave It.

Hardest thing for a new brewer like myself to do. I use buckets so I'm not tempted by the dancing yeast show. I will check for blowoff first couple of days and then literally walk away for 2-3 weeks. Just leave it be. It is not easy, but you'll be glad you did.

 

[ChelisHubby]

I am a beginner also, I am doing the 5 gallon batches so I can taste how the beer ages and share with friends. and I only have to brew every three weeks or so. If you have the room to keep the larger carboy and boil pot and other items I would recommend that you consider the same. just watch sanitation and keep some control on the tempature and you will have no problem making good beer. Now if you are a perfectionist and want to make great beer the sky is the limit to space time and money. Leave the beer alone for 2 weeks or more after the krausen drops as your beer is improving, the yeast is cleaning up its waste and the flavors are smoothing out.

 

[ChelisHubby]

I am a beginner also, I am doing the 5 gallon batches so I can taste how the beer ages and share with friends. and I only have to brew every three weeks or so. If you have the room to keep the larger carboy and boil pot and other items I would recommend that you consider the same. just watch sanitation and keep some control on the tempature and you will have no problem making good beer. Now if you are a perfectionist and want to make great beer the sky is the limit to space time and money. Leave the beer alone for 2 weeks or more after the krausen drops as your beer is improving, the yeast is cleaning up its waste and the flavors are smoothing out.

 

[chabuhi]

Thanks guys!