Water as hot as you can make it, carboy brush, and 1 Step. I let mine soak for a few days.
hot water, oxy clean a few days, carboy brush.
Warm water & Cascade Crystal works form on the tough stuff. I usually use Star-San & a carbouy brush for regular cleaning.
usually use a carboy brush when oxy doesnt cut through that top ring. It seems to sometimes need to be broken up a bit before the oxy will dissolve it.
I made a drill powered carboy scrubber similar to this:
(not my pic or idea)

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Idea found here: http://www.homebrewtalk.com/f51/buh-bye-carboy-brush-286700/
It works great. I noticed that my carboy brush was scratching my glass carboy when I had to bend it at a sharp angle to get the krausen off.
I tried one of these, and it works great. I only use about 2" worth of water and a dash of Oxyclean as well. Run it up and down the carboy for about 5 minutes, and it is clean as new.
Nice, thanks for bringing this to light. I just got finished cleaning my 6.5gal tonight. The oxy clean had no problem removing the ring left by the krausen, but the oxy actually left a ring that I had to use the carboy brush on to remove (I think I used way too much

). I hate that brush, it lacks bristles were you need them the most, on the tip, and its awkward to use. Starting a Home Depot list right now.
Originally Posted By redneck55:
Hot water and PBW cleaner.
+1
Originally Posted By Crito:
Originally Posted By redneck55:
Hot water and PBW cleaner.
+1
+2
PBW is miraculous stuff.
The "carboy scrubber" shamois-spinner posted above helps out in-conjunction-with PBW so you don't have to burn through 5 gallons to clean every carboy.
Though, it doesn't go bad and I just keep my PBW in a spare keg between cleanings - ditto for Star-San. It works in my "cascade" type system very well:
4 carboys (cleaning, clean/standby, primary ferm, secondary ferm) and 4 kegs (cleanser, sanitizer, dispensing, conditioning).
When the dispensing keg kicks, I do the following:
* Conditioning keg to dispensing
* Cleanser into kicked keg
* Rinse residual cleanser out of clean keg, pour sanitizer into it
* Secondary fermentor into the sanitized keg. Prime, seal, and purge. Set to conditioning.
The fermenters work the same way, except I lose about half a gallon of cleanser and sanitizer every time I roll them over (I don't pour back into the kegs). So while I'll make up 5 gallons of each at a time, it'll take me at least 6 months to go through it all. I've been brewing for years and I still haven't kicked my one big jug of Star-San or my big tub of PBW. Just buy those in bulk, you'll use them eventually.
Glass? Use rubbing alcohol and coarse salt.