Luis Coentrao wrote:How do you monitor the ongoing fermentation inside the Keg? Take samples to check SG? Measure head pressure with a Spundung valve?
i really don't think you get any information from looking at fermentation. from experience with the yeasts that i use, i know more or less when they are done, and i give them lots of extra time to finish their job and clean up any bi-products. for diacetyl producers, or yeasts that like to quit early, i ramp up the temperature as fermentation progresses. i give everything at least a week at or above ferm temperature after i'm pretty sure it's done. things can only be better if you wait a little extra time; yeast attenuates, diacetyl and acetaldehyde are cleaned up, yeast continues to drop out of suspension, tiny hop and grain particles also. if it's an unfamiliar yeast, or in the rare event that i need to make a beer quickly, or with a lager (which is still quite mysterious to me), then i may start taking SG samples using a wine thief as fermentation is progressing. but for the familiar yeasts i only take a final gravity reading when i'm transferring to serving (or dry-hopping) keg. if i had a conical (well, i do have one but i am not using it...) i would maybe take more frequent readings, definitely for lagers and other slow yeasts.
Luis Coentrao wrote:If we want to control fermentation temperature, just put the keg inside a fridge.
with saccharomyces i never ferment without controlling temperature. the only times i do that is with brettanomyces (which i use frequently as the only yeast), as the strains i use ferment perfectly at the ambient temps in my house, these i ferment in a (speidel) plastic bucket thingy.
Luis Coentrao wrote:Do you find any advantage of this techinque, in comparison with glass carboys?
i can't really compare to glass carboys, i have some smaller (10, 5L) glass jugs for extra wort and small experiments but i don't use big glass things!
Luis Coentrao wrote:Let me get it: when you use a corny keg as primary fermentor, you substitute the dip tube by a short one, let both short tubes open to atmosphere to purge the gas and off-flavors from fermentation, and at the end you siphon the beer to a secondary Keg.
i put in short dip tubes, but from these connectors i run tubing into a bottle of sanitizer, not open to atmosphere. i'm not against open fermentation but i don't do it. but yes open to atmospheric pressure if that's what you mean. at the end the beer goes into the serving keg, unless i'm using an intermediate for dry hopping.