Last couple batches not reaching expected FG…

[jmfitzgerald]

So I’ve been racking my brain a bit…. The last couple of batches I’ve made aren’t fermenting out as dry as I’d like them to be, or as beer smith estimates them. I’ve gone through about everything and i can’t come up with a common denominator, so i thought I’d throw it out here for any ideas. Here‘s more info and things I’ve ruled out.

-Same experience for lagers and ales, and all different styles.
-Same experience using RO water and carbon filtered home water.
-I’ve mostly hit all OG’s, so i’m getting proper mash conversion, and I’ve confirmed my mash thermometers are calibrated.
-all have been fermented in a temperature controlled fridge with a thermoprobe into a fermzill, also using a Tilt. so confirming within a degree or 2 that the tempatures are correct, also the FG is within a point of a hydrometer calibrated to 60 degrees.
-biggest head scratch and reason I’m finally bring this up... I’ve brewed an American light lager, now on my 6th batch of the same recipe. Step mashed at 142 and 156 recirculated through a RIMS tube with a 1.038SG and 1.006FG. Always hitting my numbers. This newest batch has been in the fermenter for 2+ weeks and its been sitting at 1.013 for the last 3 days now. Yeah, it may not be totally done, but it’s not going to drop 7 points. maybe 1 if i get lucky at this point…. this is the first time not hitting my expected FG and this recipe, which is making me think, why have the last couple of brews and now this, that is a very well tried and true recipe not finishing out? What’s going on? Only common denominator is the fermenter itself. Ever since i got the fermzilla, and no I’m not doing any pressure fermentations, only using it for clean oxygen free transfers, but i don’t know why that would change anything….

any thoughts on why my last couple of brews are finishing out as estimated they should???

 

[micraftbeer]

Yeast age and/or oxygen could affect. I didn't see that in your list. If your yeast is near its shelf life, you'd probably want to be doing a starter, and all yeast like oxygen added to wort. Maybe you were getting by before, and now last couple batches this has come up.

 

[TheMadKing]

What were you fermenting in before?

You said you checked your mash temp thermometers so that's a good place to start troubleshooting

Did you check your fermentation temperature calibration?

Have you changed your oxygenation routine?

Did you change your yeast nutrient routine?

Did you change how you are recirculating through your rims tube? If it's getting overheated in there, it could be denaturing enzymes. I've done that with my HERMS coil and too hot of HLT

How about ingredients? How old is the grain?

Do you monitor for mash pH? Maybe there's been a significant change to your water supply

 

[madscientist451]

I'll go out on a limb and say its your mash. Try a single infusion OVERNIGHT BIAB mash. You'll get a super dry (maybe some would say over-attenuated) beer.

 

[hotbeer]

If you aren't controlling the temps of the beer and the ambient temps when you started fermenting where higher than what they are now, then that might be slowing things down to a crawl or even stop altogether.

Which way does your Tilt show the temps going the last few days your SG was getting lower?

 

[jmfitzgerald]

Yeast age and/or oxygen could affect. I didn't see that in your list. If your yeast is near its shelf life, you'd probably want to be doing a starter, and all yeast like oxygen added to wort. Maybe you were getting by before, and now last couple batches this has come up.

don't think it's a yeast thing... all of of these batches have been single pitch, fresh yeast from either White Labs or Wyeast, all grown with a starter on a stir plate, mainly to confirm yeast activity before pitching into wort...

 

[jmfitzgerald]

If you aren't controlling the temps of the beer and the ambient temps when you started fermenting where higher than what they are now, then that might be slowing things down to a crawl or even stop altogether.

Which way does your Tilt show the temps going the last few days your SG was getting lower?

no, my fermentation fridge is temperature controlled with my lager profile via a STC1000 and a thermoprobe going into the center of the fermenting wort. comparing those temps with the tilt temps, they are with in a degree or so.

i did get one more point out of it yesterday, so down to 1.012 now, but by looking at these graphs, i sure don't think it's gonna get another 6 points out of it. it's just strange that this is happening on my last 4 batches, all differing styles, yeasts, etc...

 

[hotbeer]

Well it looks like something starting to happen again as you let it warm up.

I've not done any lagers as I don't have the equipment or ambient temp conditions to do them. You didn't cool it too fast from the get go did you? Otherwise I'm well outside my knowledge and experience and my mouth fingers will get me in trouble quick.

 

[Beermeister32]

Sometimes lagers continue fermenting slowly even after two weeks. I’ve even seen them continue to drop into week three, four etc. Depending on your fermentation chamber temperature, colder takes longer, if you ferment at 48F it will take longer than at 56F for example.

I’d then run the temperature up to 68F for a D-rest for a few days, then re-check your gravity. That usually finishes it off sufficiently.

If this continues, place the lager in a keg with a couple tablespoons of corn sugar, set it off on the floor somewhere at room temperature and forget about it for a few weeks. Move onto other beer projects, prepare for your next batch. Usually it will continue to drop and finish up on its own.

 

[TheMadKing]

don't think it's a yeast thing... all of of these batches have been single pitch, fresh yeast from either White Labs or Wyeast, all grown with a starter on a stir plate, mainly to confirm yeast activity before pitching into wort...

Can you describe your starter process?

How many liters, how long on the stir plate, do you check the date on the yeast before propping up, etc?

 

[camonick]

I know nothing about TILTs and their reliability, but have you verified the readings are accurate against a regular hydrometer? All the bells and whistles might be cool, but it’s an electronic device after all.

 

[wepeeler]

I know nothing about TILTs and their reliability, but have you verified the readings are accurate against a regular hydrometer? All the bells and whistles might be cool, but it’s an electronic device after all.

I was going to chime in and say just that. My Tilt is ALWAYS a few points off the manual hydrometer. I calibrate in water before every use, and it usually reads the SG right on. I also use the Tilt for more of a trend finder, like when to DH, than an actual precise reading for FG.

 

[jmfitzgerald]

I was going to chime in and say just that. My Tilt is ALWAYS a few points off the manual hydrometer. I calibrate in water before every use, and it usually reads the SG right on. I also use the Tilt for more of a trend finder, like when to DH, than an actual precise reading for FG.

agreed 100%, it's a trend finder for sure. the tilt is great, but i really only use is for reference during fermentation, but the numbers i'm speaking of are off a precision hydrometer. after calibrating the tilt before every use, i find the tilt is within a point or 2 when i compare the hydrometer, so close enough to see when it's getting close to DH, cold crash, etc.

and in reference to the starter procedure, it really depends on what i'm brewing, yeast cells needed, etc. usually always do a minimum of a 1L starter, on a stir plate for about 16hrs. some batches 2L or done step starters to get i higher cell count. always check dates on each yeast pouch. i've been getting some very fresh yeast lately from my local home brew shop and everyone i've done, i can definitely see activity in the flask. after pitching, each batch shows activity pretty quick too. so i really don't think any of these last 4 batches, of different styles, have been a yeast health issue either.

 

[wepeeler]

agreed 100%, it's a trend finder for sure. the tilt is great, but i really only use is for reference during fermentation, but the numbers i'm speaking of are off a precision hydrometer. after calibrating the tilt before every use, i find the tilt is within a point or 2 when i compare the hydrometer, so close enough to see when it's getting close to DH, cold crash, etc.

and in reference to the starter procedure, it really depends on what i'm brewing, yeast cells needed, etc. usually always do a minimum of a 1L starter, on a stir plate for about 16hrs. some batches 2L or done step starters to get i higher cell count. always check dates on each yeast pouch. i've been getting some very fresh yeast lately from my local home brew shop and everyone i've done, i can definitely see activity in the flask. after pitching, each batch shows activity pretty quick too. so i really don't think any of these last 4 batches, of different styles, have been a yeast health issue either.

How does the Tilt FG compare to your manual precision hydrometer?

The next step would be to make sure volumes aren't off. I know you said your thermometer is calibrated for the mash temp, so that shouldn't be the issue, but mash temps are important for producing fermentable wort. So, you could technically get an accurate OG with a higher mash temp, but if the mash temp was higher than expected, it wouldn't be as fermentable, leaving behind residual sugar and a higher FG.

Also, for lagers, a 1L starter is definitely not enough yeast. A 2L starter most likely isn't enough. Punch your numbers in here and see where you're at: Homebrew Dad's Online Yeast Starter Calculator