BIAB- High F.G. Problem

[johnford]

Hi Folks,

I have recently began all grain brewing using the BIAB method, after 2 years using extract and speciality grains. I have made three 5.5 gallon batches so far and 2 of those (both dark beers) had a high final gravity of 1.02.
Here's the grain bill and adjuncts used for my latest batch-

9lbs pale 2-row
8ozs Roasted Barley
8ozs Chocolate Malt
3ozs Brown Sugar (10 mins)
3ozs Raisins (10 mins)

My strike temp. was 160 degrees, mash temp was approx. 152-154 for 1 hour.

I used Safbrew S-33 dry yeast sprinkled onto the wort at a temp of about 72 degrees.

After about 6 hours the airlock on the fermenter was bubbling very vigorously-which continued for about 6 hours then stopped suddenly. I swished the buckets around a bit, no more activity was apparent. Took a gravity reading after 7 days and reading was 1.02. Starting gravity was 1.05.

I pitched a packet of Safbew-S-04 on the wort on day 7 and 4 days later still no sign of any further airlock activity.

So frustrating after all the time and effort. Any advice would be very much appreciated.

John.

 

[zachattack]

I'd start off by make sure your thermometer is calibrated. Also, are you using a hydrometer or refractometer?

 

[johnford]

I checked my thermometer recently and it seemed okay. I'm using a hydrometer.

 

[Seven]

What was the O.G. of your beer?

I've never used S-33 yeast but the Fermentis spec sheet says it's "low attenuating" ???

I'd also suggest re-hydrating the dry yeast instead of direct pitching it onto the wort next time.

Are you controlling fermentation temperature?

 

[Yooper]

I mash temp of 154 should be ok- but double check your thermometer because that's on the verge of being too high and causing a less fermentable wort (and a high FG) with lots of body.

If your last few batches finished higher than desired, first try mashing at a lower temperature, like 151, and making sure to aerate/oxygenate the wort very well before pitching yeast.

 

[johnford]

My O.G. was 1.05. I've never rehydrated ale yeast before but might give that a go next time, thanks for the advice.

I'm not controlling or monitoring the room temperature after the yeast has been pitched, and hitting F.G. hasn't been a problem in the past so I've not worried about that.

Maybe I need to re-check my thermometer and aim for a lower mash temp-that sounds like it might be it.

I'll try these things out next time for sure so thanks for the help. And for this batch I guess I'll bottle it in a couple of weeks without priming sugar and keep an eye out for over carbonation/bottle bombs!

 

[Brew_Bro]

Yeah, with an OG of 1.05, I'm going to agree with previous comments concerning your mash temp, sounds like it's too high.

 

[T-Wayne]

I had this problem a couple brews ago. I was freaking out thinking i had some bad yeast. Turns out, my thermometer was not doing its job and I mashed way too high (Probably around 158).
The beer was sweet and thick.

 

[m00ps]

You may have a leaky lid. So there is fermentation activity, but its not going through the airlock. Try pressing down on the lid and watching the airlock. I've had this happen to me before

Also, I'd suggest pitching your yeast about 10 degrees cooler. Mid-60s will minimize off flavors. Rehydrating dry yeast also helps a lot if you aren't willing to make the move to liquid yeasts. But if you are going to invest the money, effort and time into brewing, I'd definitely recommend liquid yeasts. Apart from US-05, there is a much better liquid variety or equivalent for each dry yeast you would use in a style. Your brews will jump up in quality pretty fast once you make the switch

 

[ReverseMonk]

What was the O.G. of your beer?

I've never used S-33 yeast but the Fermentis spec sheet says it's "low attenuating" ???

I'd also suggest re-hydrating the dry yeast instead of direct pitching it onto the wort next time.

Are you controlling fermentation temperature?

[1] pack of S33 combined with a slightly high mash temp is a good recipe for low attenuation. I know most of the dry yeast says you can pitch a single pack for a 5 gal batch, but I highly recommend pitching 2 packs with proper re-hydration.

 

[LLBeanJ]

I had this problem a couple brews ago. I was freaking out thinking i had some bad yeast. Turns out, my thermometer was not doing its job and I mashed way too high (Probably around 158).
The beer was sweet and thick.

I've had the same issue. I was using one of those $20 CDN digital thermometers and getting high FGs. Both boiling and freezing calibration was within 1°, but I was suspicious about its accuracy at mash temps. Then I received a Thermapen for Christmas and discovered that the CDN was reading 4° low at mash temps. Problem solved.

 

[johnford]

You guys rock-thanks for the solid advice. And good to know I'm not the only one who's had brewing woes.

 

[T-Wayne]

...Then I received a Thermapen for Christmas and discovered that the CDN was reading 4° low at mash temps. Problem solved.

Thats exactly what was happening for me.

 

[DurtyChemist]

Mash at 150 using the same recipe and see what happens.