This is my 4th or 5th batch. A nut brown ale I boiled three days ago.
I noticed that half the krausen is fine, light colored bubbles and the other half is gross-looking but perfectly normal krausen. What in the world would cause this?
It’s normal, don’t worry about it. It’s just the scuzzy trub that forms on top of the yeast during primary fermentation. It’s not always uniformly distributed.
About the only thing I can conceive of is that the “light” bubbles are on the side of the carboy that faces the door of my closet. This closet has an electric water heater in it that keeps the closet at a constant 72 degrees with the door closed. During the first couple of days of really active ferm, I crack the closet door a few inches to try to lower the ferm temp to ambient house temp which is a few degrees cooler (67 during the day, 59 at night). After the active ferm takes place and cools down a bit, I close the closet door and hold it steady at 72F.
That’s the room temperature? That’s a bit warm as your beer temperature is probably 5 degrees higher than that. You may notice some sharper alcohol flavors in your finished beer. You want the room to be lower, closer to 64F if you can help it. But it’ll really only be a problem on high gravity beers.
I’d say the right half of the batch is ruined but the left half is fine, carefully siphion the left side off leaving as much of the right side as possible… 8)
Seriously, it’s fine. Most likely the break and hop material came up at the first of the fermentation and got pushed to the side as the fermentation picked up. I usually get light and dark splotches on my caps, it all settles back down.
So is that one of the new big mouth bubblers?
You freaked me out just a little. I read your post then ran to my closet (like that would do any good) to check my temps. The strip on the carboy reads a cool 66. Just a couple of degrees warmer than my 10 day old Caribou Slobber. It was as high as 74 on the first night so you gave me something to worry about for the next month. Thanks!
As long as I keep the closet door ajar, the temp stays around 66 or so (ambient house temp). But if I close the door, it stays a constant 72. So, I keep the door ajar for the first few days then close it when the yeast applause calms down a bit.
It are.
It’s the 5 gallon version and has worked well (no blow-off) for two brews so far. My 6 gallon standard carboy is busy. 
Glad you spoke about the big mouth as I have been eye-ballin’ them myself for this coming year. Oh, and when you siphon off the bad right side, send it to me to dispose of!
Any chance the carboy is on an angle?
No, no chance the carboy is on an angle. Whatever is was, it’s almost all cleared up now. Now only a bunch of nice clean white bubbles. Very interesting whatever it was.
For those that asked for the bad half, you can have it when I’m finished with it.
Thanks for all the replies!
That’s the room temperature? That’s a bit warm as your beer temperature is probably 5 degrees higher than that. You may notice some sharper alcohol flavors in your finished beer. You want the room to be lower, closer to 64F if you can help it. But it’ll really only be a problem on high gravity beers.[/quote]
I lived in an apartment once where a very large walk-in closet was the only place I had to ferment in and keep all my homebrewing supplies. It had an unusually high ambient temperature in the winter months, somewhere in the upper 70’s. The beers in fermented in that closet were the most incredibly aromatic ones I’ve ever made in all my years of brewing, especially the dark ones. They were also quite complex in flavor, rivaling any commercial beer I’ve ever had. I can’t say for certain that the high temperature of that room was entirely responsible for everything I experienced with those beers, but I’d have to say it was a largely influential factor. So, all in all, I think it’s safe to say that some yeasts can definitely work very comfortably with somewhat elevated ambient temperatures.
What yeast are you using? Most have a recommended temperature range that you can look up online. I can tell you from personal experience that if you exceed that limit you’ll have some off flavors… I wouldn’t describe them as complex, more like undesirable, but taste is subjective and somebody else might find it ok. You’ll still make beer!
