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Slow fermentation vs. aggressive fermentation

Hi All,

I just brewed my 3rd beer yesterday and now I have a new question about fermentation. Sorry in advance if this is a long and wordy post :slight_smile:

My first two batches - Caribou Slobber & Brickwarmer extract kits - had very aggressive fermentation within in the first 12 hours or so. It looked like a krausen monster was trying to escape from the carboy, and I quickly learned the importance of a blow off tube. Bubbling was constant and fast during the first 24-36 hours, then quickly settled down. I used the dry yeast options for both of those.

Now, I made my third batch yesterday (St. Paul Porter extract kit), and it has something different going on. After 16 hours I’m only seeing a small layer of krausen on the surface and the bubbles are only every 3-5 seconds. I have a blow off tube in, but I’m realizing I don’t even need it. This fermentation is… lazy, I guess. I used the dry yeast option for this batch too.

I used the dry yeast option for all 3 beers because I’m still getting used to the basic process and don’t feel ready to make a yeast starter on top of everything else. I also aerated them all the same way, by rocking the carboy back and forth to splash for 2 solid minutes.

Honestly, the only differences between this porter and my first two beers are:

  1. I pitched the yeast a little cooler this time. My previous two were pitched at 78* F, but I pitched this one at about 72*.

  2. This is my first time using a swamp cooler to control temperature. My first two fermented at 72 - 75* F, this one is reading 68* F (approaching 66*) on the fermometer.

  3. Although they were all dry yeasts, they were different: Danstar Windsor vs. Safale S-04 vs. Safale US-05.

Any guesses as to why I’m getting a slow fermentation on this batch as opposed to the quick/aggressive ones of my first two beers? And is one type of fermentation better than the other? I’m not sure if it’s because I’m controlling my temps this time around, or maybe I did something wrong without knowing. I appreciate any feedback.

Different yeasts, different temperatures, different ingredients, and different gravities (as well as many other things) all can contribute to the aggressiveness of the fermentation. The good news is, as long as it’s visibly fermenting, things are going as they should be. Best thing to do it just wait a week and let it do its thing. Then take a gravity reading. My guess is everything is just fine :slight_smile:

Thanks for the advice, Matt. I’ll just sit tight and be patient, which I’ve learned is the most challenging aspect of brewing for me :slight_smile: But unfortunately, I won’t be taking a gravity reading. I made the mistake of putting a hydrometer (and other brewing supplies) on my Christmas list, so I’m stuck waiting until December 25th before I can move forward with all the things my wife is getting me (yeast starters are on hold too, since she’s also getting me a flask and stir plate).

I can save you some money and time. You don’t need a flask or stir plate to make a starter. Check out Yeastcalc Look at the option for intermittent shaking. I like using a 1.5 gallon pickle jar for my starters.

How aggressive a fermentation is also depends a lot on wort temperature. Fermenting an ale at 72° to 75° will produce some off flavors. Not a bad temperature for a saison yeast though.

Purchase one less 12 pak and you have saved the dollars for a hydrometer.

I like my 1g apple juice jug for starters. I works great on my homemade stir plate. Total cost around $20.

Like mentioned, the warmer temps helped with the fast/aggressive fermentation. Which is better is up to you. Some like the flavors of the warmer temps.

Pick a hydrometer up on the sly. They’re cheap, indispensable, and fragile. It’s always good to have a spare.

I use a 64oz growler jug for my starter and have never had a problem. I’ve moved away from making starters. I try to make a beer that is lower in alcohol than the beer needing a starter, but using the same yeast. For example, I just made the Petite Saison d’Ete so I could use the yeast from that to make the Saison de Noel. I add some water that’s been boiled and cooled to the yeast cake, swirl it around, let the carboy sit on it’s side so it can settle, pour the “washed” yeast into my growler and just let it set for no more than a day in the room where the ferment will take place and pitch about a quart of that into the next beer. This approach saves you a few bucks and helps you learn/experience what the one yeast can do to two different beers. It’s pretty easy to do too. I use starters now only if I’m making a lager or if I’m pitching yeast that I’ve saved. I’m hoping to get my hands on Wyeast’s Belgian Stout yeast. I’ll make a Paterbier as my “starter” and then make the Mustache Envy.
I suggest you get the hydrometer. It’s cheap and will give you some assurance that fermentation is complete. It sounds like you could use some assurance with this porter.

#2 is the reason.

You are running too hot. If what i found is accurate, the recommended ranges are…

Danstar Windsor 64 to 70F
Safale S-04 59 to 75F
Safale US-05 59 to 75F

The swamp cooler is good, keep the fermentation temps in the lower third of the yeast recommended range.


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