Stuck Fermentation with Lactose?

[Colorado68]

Hello,
Hope someone can help me out here.

Brewed an oatmeal milk stout three weeks ago w/ 1lb lactose last 10 min of the boil.
Started with 1.060 and fast (withing 5 hours) fermentation activity.
After a week it was only down to 1.030 and now two weeks later sitting at 1.028.

Does this sound like a stuck fermentation or is the lactose throwing my hydrometer off?

Thanks for any insight.

 

[brdb]

I brewed a milk stout a few weeks back and had something similar happen, so 1.028 could very well be your FG. In my case, my OG was 1.063 (also added 1lb lactose) and my FG wound up being 1.027 although the final few points did take around 5-7 days to fully attenuate (total of 3 weeks fermentation time). What does your recipe look like?

 

[beergolf]

With a pound of lactose it may not get much lower. If your recipe has some more unfermentables or you mashed on the high side it is most likely done. Give a little more time but if it does not go down it is probably done.

 

[chickypad]

The lactose doesn't throw your hydrometer off. It raises the FG by adding all unfermentable sugar, but the reading is correct. In other words, a lb of lactose in a 5 gal batch adds about 7 gravity pts to both the OG and FG. If your estimated FG is based off software be sure that it is treating the lactose as unfermentable, for example in Beersmith you need to specifically check a box on the grain page.

 

[Colorado68]

The lactose doesn't throw your hydrometer off. It raises the FG by adding all unfermentable sugar, but the reading is correct. In other words, a lb of lactose in a 5 gal batch adds about 7 gravity pts to both the OG and FG. If your estimated FG is based off software be sure that it is treating the lactose as unfermentable, for example in Beersmith you need to specifically check a box on the grain page.

You nailed it!
I am using BS and didn't realize there was that check box. Now I feel better it's closer to what I should expect (1.026)

Thanks a lot!

BTW.. here's the recipe brdb asked about:

 

[brdb]

BTW.. here's the recipe brdb asked about:

Yeah I would say 1.028 is about right when we're talking 1lb of lactose and ~60% base malt.

 

[kettlehead]

I brewed a Milk Stout and added 2lbs lactose on mistake should have been 1lb. OG was 1.067 FG was 1.028. Waiting impatiently for carbonation. Tasted good going into bottles.