[jamminbrew]

Yesterday I brewed an oatmeal stout using extract and seeping grains.  I used wyeast irish ale yeast.  I looked at my carboy this morning, and about 8 inches up from the bottom is a cream colored ring, about a 1/2 inch wide.  I'm not terribly worried about this, as I am assiduous about my sanitation and cleaning, but was curious as to what it is.  Anyone ever encounter this? Thanks!

[tschmidlin]

I've noticed that I sometimes get sediment clinging to the sides in a ring that sounds like what you're describing.  The ring only happens in some of my carboys even when I split 10 gallons of the same batch between two.  I'm assuming the inside surface is not completely smooth and there is a slight ledge or slope where sediment can get stuck.  It has never seemed to affect a batch, but I usually use different yeasts when I split a batch.

Anyway, does it sound like the same thing, or something else?

[jamminbrew]

Well, it happens to fall in between two ridges, and I've also noticed that below the ring, the fermenting wort is considerably darker than above it. I have used this carboy for 4 other brews, (I have three glass carboys) without seeing this occur.  I'm sure it will be fine, as it is already bubbling merrily away. 

[tschmidlin]

If it's noticeably darker on the bottom, it might be that it is not properly mixed - did you do a full boil, or did you top up with water and give it a shake?  It might be worth it to give it a good shake to mix the layers and disturb that ring which should fall to the bottom.  Just a thought based on what I'm picturing.

[jamminbrew]

I did a full 60 minute boil with 2 1/2 gallons, and after chilling, I topped it off. I shook it vigorously for 2-3 minutes to aerate.  After pitching the yeast, I shook it briefly (but gently this time) again to distribute the yeast.  I will shake it again and check on it in a while.  Thanks, Tom for your time and advice!

[tschmidlin]

Yeah, ok, so it sounds like it's not mixed well.  By full boil I meant full volume, sorry for not being clear.  Don't trust any hydrometer readings you took   Next time you might add a gallon or so of water to the carboy first , add your wort, and then shake a lot to mix it and aerate it.  Then top it up to your final volume and mix some more.  Or use a mix stir, they are relatively inexpensive if you already have a drill to attach it to.
http://morebeer.com/view_product/19688/beerwinecoffee/Yeast_Stirrer

But above all at this point, RBWHAHB, it will be fine.

[jamminbrew]

Ok, just checked on it.  After shaking it again, the sediment ring disappeared, and the color evened out.  But now after 2 hours, it has separated out into lighter/darker again.  It's not a gradual changs, but a distinct line.  I'm not worried, it is visibily fermenting, but I guess I don't understand why it separates.

[bluesman]

Or use a mix stir, they are relatively inexpensive if you already have a drill to attach it to.
http://morebeer.com/view_product/19688/beerwinecoffee/Yeast_Stirrer

I use a mix-stir rod with a cordless drill to not only aerate the wort but also to blend in any water additions as well. It will do the trick for sure.