US-05 attenuation only 75%

[hilljack13]

Just kegged my latest brew this morning. IPA using S-05. I wanted to try something new so I did a step mash on this, pitched two satchets and fermented 14 days at 65F. I usually get to the end using S05 by 8-10 days, but this one kept going so I assumed it was the mash.

So, OG was 1.081. I skipped using my Tilt this time since I knew I wanted to go longer on fermentation time. My hydrometer reading today showed 1.020. Right at 75% which I thought was normal until I looked at Fermentis and they show 78-82%. I ended up a bit low here and not sure why. I have gotten higher and I thought that the step mash was supposed to help with fermentability. Maybe I am reading into that part wrong?

Still has a good taste and has 8.01abv so it will get the job done. I just assumed it would have been higher. Is there anything I should have done to get a higher attenuation?

 

[Bobby_M]

What was the mash schedule? The grain bill will also affect fermentability.

 

[hilljack13]

105F - 10 min
122 - 20
145 - 40
158 - 20
170 - 10

I don't remember where I found it at and realize it isn't needed, especially for an ale. Just wanted to see what it would do.

14lb - 2-Row
0.75lb - Carapils
0.50lb - Carastan
1lb corn sugar @10min

 

[MikeCo]

Next time consider simplifying the mash to a single infusion and keep it at 150 to 152F. The sugar helps make the beer more fermentable. You could reduce the amount of carapils and carastan to reduce FG. Did you use any software for the recipe - what was the predicted FG for the recipe and mash profile?

 

[Petdrummer]

65 at the bottom end of the range for s-05. Could be an issue particularly with the high og. You might want to step the temp up a few degrees into the 68 to 70 range and see if fermentation picks up. My last batch with s-05 started at .056 and stalled for days at at about your gravity until I warmed it up to around 70. It dropped to .011 in 48 hours.

 

[hilljack13]

Next time consider simplifying the mash to a single infusion

I normally do this. Like I said this was just something I tried only for this brew.

Did you use any software for the recipe - what was the predicted FG for the recipe and mash profile?

I use the GrainFather app. It showed OG 1.068 and FG 1.006, but I was using 80% attenuation so that was part of it.

You might want to step the temp up a few degrees into the 68

I usually go 68 with 05, I did a stout last year and I remember bumping the temp up from 65 to 68 and it did ferment from 1.083 to 1.016. I should look at these old recipes more often.

 

[VTMongoose]

Are you measuring the temperature in the mash itself, in multiple places (inside, outside, top, bottom), while mashing? Are you stirring the mash? What kind of system are you brewing on? RIMS/HERMS?

 

[hilljack13]

Are you measuring the temperature in the mash itself, in multiple places (inside, outside, top, bottom), while mashing? Are you stirring the mash? What kind of system are you brewing on? RIMS/HERMS?

GrainFather G40. Has multiple temp sensors and it recirculates the mash the whole time.