Anvil Foundry 6.5 - High FG

[ModlrMike]

So I got myself an Anvil Foundry 6.5, and after four batches, I'm still getting high finishing gravity. My typical mash temp is in the 150F range, and with the exception of the last batch, I typically don't do a mashout. Next batch I intend to do a comparison of the temperature probe vs an external thermometer, to see how accurate the temps are. Other than that, any suggestions on having a more fermentable wort?

 

[jdauria]

Are you using a pump to recirculate the mash? If not, are you stirring the mash several times during the mash? The Anvil thermometer is calibrated to read the middle of the mash temps, so if you are not recirculating or stirring, you will have a hotter mash towards the bottom causing more unfermentable sugars. Try stirring the mash every 15 minutes, if it still happens, try mashing at 147-148 instead.

 

[ModlrMike]

Yes, I am recirculating, and stirring. But I'm only lightly stirring the top of the mash. Maybe I should be more aggressive.

 

[doug293cz]

What are some of the recipes (just the grain bill is all that's needed) that finish with high FGs? Just something to look at in case it isn't off temps.

Brew on

 

[youngdh]

Are you hitting your OG into the fermenter? If so, a high FG isn’t a function of your Anvil but is due to fermentation issues.

 

[ModlrMike]

OG is usually within a point or two, and I've not changed anything regarding my fermentation process. Yeast nutrient in the wort, and good temperature control.

 

[tracer bullet]

Agreed it's either a temperature thing or a yeast thing.

I have found that mine always reads about 2 degrees over reality. if I set it for 153 I'll get 151 in my grain. I do recirculate and also occasionally stir and lift / lower the basket to mix in the dead space. So it could be partly dependent on those things. You'll definitely need a trusted thermometer to figure it out.

I suspect you'd have to be way off to make a big difference. I'm leaning towards a yeast choice / pitch rate / temperature kind of thing affecting your FG's.

Assuming you are reading them correctly to begin with. Refractometer (and if so, converted?) or hydrometer?

 

[youngdh]

OG is usually within a point or two, and I've not changed anything regarding my fermentation process. Yeast nutrient in the wort, and good temperature control.

So mash and boil process are working fine. Issue is the yeast isn’t fully attenuating or maybe it is for the strain you’re using. How old is the yeast? Is it liquid or dry yeast. If liquid are you making a starter? If dry are you rehydrating?

 

[ModlrMike]

Having given it some thought, it's essentially the last 3-4 batches (which were all done on the Anvil), so I'm leaning more towards a stuck fermentation. My immediate response will be to rouse the yeast, and add some energizer, when I get some. Going forward, I think I'll change my process. I'm using the pump to transfer from the Anvil to the fermenter, and I'm not convinced I'm getting enough splashing or aeration. What I intend, is to get an aquarium pump and air stone, and give the wort 5 or 10 minutes of air before I pitch the yeast.

 

[ModlrMike]

So mash and boil process are working fine. Issue is the yeast isn’t fully attenuating or maybe it is for the strain you’re using. How old is the yeast? Is it liquid or dry yeast. If liquid are you making a starter? If dry are you rehydrating?

Fresh yeast strains that I have experience with. I always rehydrate. I think I may not have enough O2 in the wort after transferring.

 

[tracer bullet]

So mash and boil process are working fine.

Maybe fine. If temps are way off, you can hit OG, but miss FG. For example if mashing is accidentally done at 157 or something.

I definitely doubt that's the issue, but it's a possibility.

 

[youngdh]

Maybe fine. If temps are way off, you can hit OG, but miss FG. For example if mashing is accidentally done at 157 or something.

I definitely doubt that's the issue, but it's a possibility.

Good point. High mash temps reduce the short chain carbs that the yeast can consume while still hitting OG.

 

[Unicorn_Platypus]

Have you double checked the thermometer is calibrated?

Years ago I had a thermometer that wasn't calibrated and all of my batches had stuck ferments.

Now I always check vs. a thermapen.

Two thermometers are better than one

Another quick test you can do is boil water and see if it reads ~212 (assuming you are not at altitude). Boiling water and not wort. Wort has a higher boiling point

 

[tracer bullet]

Still interested in how you are reading FG.

 

[ModlrMike]

I have two refractometers. One in Brix, and the other in SG.

 

[tracer bullet]

If you aren't "correcting" for the presence of alcohol, you'll get bad readings. Look into it.

If you have a hydrometer, try it out.

 

[Exception13]

I have two refractometers. One in Brix, and the other in SG.

Is it possible you aren't correcting your refractometer readings on the fermenting wort? A calculator like this might help.

Cheers!

Chris