Stuck Fermentation. Time to re-pitch?

[John Spiegel]

Brewed a milk stout, OG 1.070, with half a pound of lactose. Fermentation looked great the first few days. Dropped from 1.070 to 1.039 in three days when airlock activity stopped entirely. I tried placing the fermenter in a warm bath tub and swirling the wort gently to restart fermentation, I even added a bit of yeast nutrient. I saw decent airlock activity while the fermenter was in the tub, but after checking gravity (it's been 4 days since I tried that), gravity has barely budged. Currently sitting at 1.037. Is it time for me to re-pitch some yeast? I have some of the same yeast (s-04) in my fridge; I'll just have to make a yeast starter with it and burn a few more days between waiting for the starter and then the re-pitched yeast to do its thing. Thoughts? I was hoping to have the beer finished in time for family coming over for Easter.

edit:
I'm wondering if the airlock activity I saw while in the tub was a result of warm air or potential off gassing from moving the bucket and not necessarily an indicator of fermentation. It was a lot of activity, so I was really surprised when I had seen no change in gravity.

 

[VikeMan]

Are you measuring with a refractometer? If so, are you adjusting the readings with a refractometer calculator?

 

[John Spiegel]

Are you measuring with a refractometer? If so, are you adjusting the readings with a refractometer calculator?

I am using a refractometer. I've used a calculator online, but like I said, the gravity has remained consistent for several days, so there's nothing to calculate for.

 

[VikeMan]

I am using a refractometer. I've used a calculator online, but like I said, the gravity has remained consistent for several days, so there's nothing to calculate for.

Are you entering both the "OG" and the "FG" refractometer readings together into a refractometer calculator (i.e. not just a brix to gravity converter)? I ask this because if you just pop up a calculator that converts "brix" directly to specific gravity, that won't be right.

 

[John Spiegel]

That was my problem. I used to using a hydrometer; first time using a refractometer. Didn't account for alcohol distorting the gravity reading of a refractometer. Converting everything using brix and looks like the numbers are right where (if not a bit under) where I expected. My recipe developer projected a 1.018 finished beer.

Pre-Fermentation
Brix 17 OG 1.070

Current Brix 9 (Read as 1.035 gravity.
Current adjusted gravity 1.014
ABV 7.2%

Thanks so much. Sorry for the newby question.

 

[ncbrewer]

You're not alone. That comes up all the time.