Slowing Fermentation advice

Ingredients
1

Brewed an Imperial Milk Stout, OG 1.102
Mashed at 150 for 60 minutes, got a nice clear runoff.
Added 1lb of lactose and .25lb of cocoa powder to the boil.
Pitched S-04, for lack of a better yeast.
Brew day was 11/24.  We’re 3 weeks later, had a nice solid start to the ferment, lots of O2 and then another dose at 12, then 18hrs.  After the 18hr aeration fermentation started.  Now we’re sitting at 1.032 and it seems to be holding.

Could this be from all of the unfermentables?  Or do you think give it more time and see if it goes lower?
Can I give it more aeration at this point and try to rouse the yeast?

2

Definitely DON’T aerate it any more now. You could try rousing the yeast but it may simply be done.

3

I would give it at least another week, but I agree with Kieth that it’s probably just done.

I also agree with Kieth to absolutely not aerate at this point.

4

Check +

5

For a brew of that strength it’s most likely done.

6

Especially if you account for the lactose, which is probably 6 gravity points.

7

What temp are you at now?  Try bringing it up a few degrees if you can.  Otherwise, another vote to not aerate at this point.  It may just be done.

Dave

8

Another vote for probably being done. With the lactose, a lower attenuating yeast, and a high OG, I’ll bet you’re as low as it will go.

9

piling on here, but my RIS typically goes from 1.100 to 1.027 and I do not have any lactose in there - so I’d expect that you’re done, son.

10

Probably done.  What was your grist bill?  What temp is it sitting at now?

Regardless, I would bet it’s most likely done though.

11

If you’re curious about whether there is any chance of further fermentation, you can try a force-ferment test.  Take a large enough sample to fill your hydrometer jar and pitch a packet of Nottingham in it.  Keep it warm (put it on a stir plate if you have one), and check the gravity after several days.  If the gravity doesn’t change with that huge load of yeast in it, you can be very sure that you are at terminal gravity.

I agree with the others in this thread that you are most likely at terminal gravity and further aeration would not be a good idea at this point.  Warming it up and rousing the yeast may do something, but the force-ferment test can let you know for sure if there is any chance.

One final thought about this is that I have had beers that I thought finished too sweet and those turned out to be some amazing beers after a long period of aging.  Your beer is at 9.3% ABV right now, so it should have no problem lasting several years in the bottle.  If you are bottle conditioning the beer, I highly recommend pitching some fresh yeast at bottling.  I’ve had big beers fail to condition because the yeast were too worn out, and a pack of dry yeast is cheap insurance to avoid that situation.

12

Also piling on here, but after counting off 6 points for the lactose you’re at 73% apparent attenuation.  That sounds pretty good for S-04.

13

Ok I fell behind on replying,
a few days later FG hasn’t moved, some CO2 is coming off, as I can push the airlock and it will eventually push back to the ‘out’ side.  Could just be gas escaping.

I’ve let it get up to 73F and not seeing a change.

Now I need to taste it and start adding back my more cocoa.