Having a Problem With Stuck Fermentation(s).

[LuNchBoX1371]

So I have been AG brewing for about 3 batches now with a 15-gallon keg set-up. I first did an AG batch with a 10-gallon igloo cooler and had no problem with any of the 3 batches not fermenting properly, but now when I am brewing with my new 15-gallon keg and burner set-up I am having a problem with stuck fermentations. Admittedly I have been brewing pretty high; the first one was at about 155 and then when I went to fly-sparge the temp. rose up to about 180 cause I left the heat on too long and couldn't get it down to temp. after it got up so I'm assuming I extracted too many tannins and during the fermentation process the yeast didn't have enough proteins and etc. to get the job done and just stalled.

On the second batch things went a lot smoother, but still I brewed a little too high. When I put in the grain I thought it wasn't going to be at the right temperature so I turned the heat up a bit, for a short time, and it went too high; I was at 160 instead of being at 156. It stayed there the whole time until the mash out. When I mashed out I tried to get it to 170 but it was at 160 and took about 10 min. to get to 170, then continued to fly-sparge and things pretty much went as smooth as possible with temp. and everything else. Then continued to varlauf and went on to the BK and everything went well.

Now as far as the cold break goes I got it down to 60* after I stopped boiling and begun to chill my wort down, through the work of a plate chiller and a hose water- that had to be 40 degrees lol. So I don't think it was the cold break that screwed me up, like it had in previous times when I had just let my beer cool down naturally in the keg and the put it in the fermenter (didn't run through that explanation cause I figured that would be self-explanatory lol). So I don't think it was the cold break, but now my previous 2 batches have had stalled fermentations at the half-way point of there fermentation process so what is going on- I have recently posted a post in this forum about what my gravity reading should be at the half-way point cause I was hoping that this didn't happen again.

So what is going on? Is it that I am brewing too hot and extracting too many tannins? Or is it something in the fermentation process, or is it just something I am doing wrong?

Eager to hear your responses and get this problem fixed. Thank you. Lunchbox.

 

[Calder]

mashing at 156 or 160 F will certainly give you a highly unfermentable wort. I aim for 150 or lower for most beers. When I want some body (Porters, Stouts, etc) I'll ferment in the low 150s.

Sounds like you mashed too high and have wort that doesn't ferment well. You might want to check your thermometer to see if it is reading right too.

You probably didn't extract tannins. That is difficult to do, and does not affect fermentability.

Yeast selection may also be a factor.

 

[BobBailey]

First off, without knowing at least the batch size, grain bill, OG and FG, yeast strain and how much yeast you pitched, it's kind of tough to point you toward the problem, let alone a solution. Any answer you get without this information is a guess.

Also, are you checking the FG with a hydrometer or refractometer? If you're using a refractometer you need to use a correction factor for accurate readings once fermentation has started.

 

[RM-MN]

Without knowing just what you are doing, if your grains are not crushed well enough (often they aren't) conversion was not over when you went to mash out and that killed the enzymes so you got a wort that has too much dextrines. For the immediate future, extend your mash to 90 minutes, do not mash out, do not fly sparge. Do a batch sparge with tap water, not hot. That will help eliminate the excess dextrines and may get you the more fermentable wort you need.

 

[LuNchBoX1371]

mashing at 156 or 160 F will certainly give you a highly unfermentable wort. I aims for 150 or lower for most beers. When I want some body (Porters, Stouts, etc) I'll ferment in the low 150s.

Sounds like you mashed too high and have wort that doesn't ferment well. You might want to check your thermometer to see if it is reading right too.

You probably didn't extract tannins. That is difficult to do, and does not affect fermentability.

Yeast selection may also be a factor.

I think that's the problem I'm mashing too high. So I'll try that with my next batch.

First off, without knowing at least the batch size, grain bill, OG and FG, yeast strain and how much yeast you pitched, it's kind of tough to point you toward the problem, let alone a solution. Any answer you get without this information is a guess.

Also, are you checking the FG with a hydrometer or refractometer? If you're using a refractometer you need to use a correction factor for accurate readings once fermentation has started.

It's a 10-gallon batch with: 20 lbs 2-Row, 4 lbs 12 oz Rye Malt, 2 lbs 8 oz Midnight Wheat, 2 lbs 8 oz Caramunich, 1 lb 4 oz carafa III, and 1lb 2.4 oz Crystal 60L. My OG was 1.081 and my FG was 1.024. Yeast strain was supposed to be American Ale yeast from wyeast but I ended up messing up my order and got an American and a London Ale yeast, I was doing a 5000 mL starter for this batch so I needed 2 yeasts, so I did a did my yeast starter out of that.

Last night- since everything has stalled- I went to the brew shop got another thing of yeast and some yeast nutrients. I put in the yeast nutrients and Pitched the yeast; after about 12 hours nothing has happened, it is still at the same SG. So I'm thinking based on what Calder said I'm mashing too high and extracting too many unfermentables. If anything I'm going to try with my next batch to mash at a lower temp. and see what happens.

 

[BobBailey]

I have to agree. Looks like the only thing really off was your mash. As Calder said, those mash temperatures will give you a dextrinous wort and thus a higher finishing gravity. I would have expected your FG to be in or around 1.020 if you had mashed around 150F. So, you don't have a stuck fermentation. You have a fermentation that is complete, but higher than you wanted.

 

[helibrewer]

You just need to dial in your temps with the new set-up. Stainless doesn't transmit heat real well so you have to be real careful applying direct heat to a Stainless mash vessel, and 10 gallon batches is a large mass to heat, there will be delays.

You need to get the strike temperature dialed in so that you don't have to apply heat. The variables are: grain temperature, desired mash temp, specific heat of the mash tun and whether you have pre-heated the mash tun. A software program like Beersmith will handle this for you using your equipment profile.

Bottom line, nail your strike temp and you'll be fine.

 

[LuNchBoX1371]

Ok cool thanks for the help guys.