Confused over 'dropping' - to aerate or not aerate?

[lancsSteve]

I'm confused by 'dropping' - and have read two diametrically opposed methods. all agree this is in early fermentation after 36-48 hours..

In one (Graham Wheeler) the idea seems to be to re-aerate the wort but drop it off the yeast head and trub - rousing and re-aerating the yeast.

Another (e.g. Horden Hillbilly's page a http://uk-homebrew.tripod.com/id24.html) is to NOT aerate but transfer carefully.



I've transferred following the latter - after 36 hours when fermentation was still VERY active but since transferring it's now very slow and no yeast head has re-formed. Is this a 'stuck' fermentation? It's in a fermentation bucket with a lot of head room and an air lock fitted so I wouldn't expect quite as rapid bubbling as in the carboy it was in before with a much smaller head space but seems very quiet.

So - what are the rationales behind each approach to dropping and any advice? IS it a good idea or are stuck fermentations a high risk? (I'm using safale-04 BTW and have read NOT to re-aerate this one e.g. Chris x-1's advice here at: viewtopic.php?f=2&t=24296&p=269609&hili ... te#p269609)

Furthermore how can you assess a stuck fermentation - take samples off and check hydrometer readings or dump sterilised hydrometer in bucket and open lid regularly to check? First seems to mean losing quite a bit of beer, latter seems to risk infection!

[Jim]

You need to check the specific gravity (sterilised hydrometer dropped in the fermenter will be fine); fermentation may be complete.

Depending on the starting gravity, final gravity can be anything from1.006 to 1.014. What you look for is a gravity close to that figure that remains stable over 24 hours.

[theoldebrewer2]

Personally, I skim the yeast head and brown scum off 3 or 4 times a day for 2 days. Transferring to another vessel will involve aeration, not needed once the yeast is working well. Also chance of airborne infection increased. I even wipe away the brown scum tide mark.

[lancsSteve]

Went from a glass carboy so skimming wasn't an option - was following horden hillbilly's step-by-step pretty much throughout and it's done me a treat but afte the event (and now waiting for primary fermentation to finish) I'm fretting (innevitably for a first AG brew) and also reading up on other aspects and finding these points of disparity.

Will take a sample soon and see how the gravity is

[Invalid Stout]

S04 goes like the clappers so it's quite likely already finished, which would explain not getting a second yeast head.

[Horden Hillbilly]

Just to clarify my methods.

If I intend to bottle the brew, I always use the dropping system, usually 36-48 hours after the fermentation has started, and I always use a tube fitted to the tap which reaches the bottom of the receiving fv. This leaves all the trub/dead yeast cells behind in the fv, including those which settle on the bottom of the fv. If these are not removed, it may cause off flavours after a few month's storage, which all my bottled beers/lagers are.

If I transfer the brew to my king keg, all I do is skim off the brown trub which rises with the yeast when fermentation starts, as these brews tend to be consumed fairly quickly! .

It is true that some yeast strains do not like being "dropped", I recall doing this with a Whitelab Burton yeast & the fermentation took around 10 days to finish after doing so. Nottingham, Wyeast 1028, Whitelab British & Brewlab standard all seem to be ok with the dropping system in my experience.

[lancsSteve]

Thanks for clarification which makes it a lot clearer - oh and thanks for the guide on your site too

And yeah invalid stout you're on the money - Just taken a hydrometer Reading and it's 10.10 reading which as mine is like most is 10.12 (once corrected) which is expected FG so guess fermentation has been a success and is finished will check tomorrow then keg

Ta all for info and help

Steve

[bobbytinner]

Could you clarify the process of 'skimming'? I am currently fermenting a 1056 strength Hollywood IPA using White Labs WLP005. It has set off like the clappers and after 36 hours it has massed a thick brown floculation. On previous brews I have skimmed by totally clearing all the top surface with a sterilsed sieve. Is this being too excessive?

Thanks
BT