Beer is fermenting but gravity remains the same

[phildo79]

Reet, so I am fermenting an imp stout in a keg and using an iSpindel to record the gravity. The OG was 1.090 and fermentation started off well. When the blow-off tube stopped bubbling, the gravity was 1.030 and it is supposed to be 1.017. I raised the temp on Sunday and fermentation appeared to start up again. The blow-off tube was producing a bubble every ten seconds or so. However the gravity has barely changed. The lowest the iSpindel has reported is 1.028 but sometimes it says 1.030. I pulled off a sample to use a hydrometer and it showed 1.030 so the iSpindel is working properly. I cannot understand why the gravity hasn't dropped after a further 3 days of fermenting.

Any ideas as to why this is happening and how to get the gravity down?

Thanks in advance.
Phil

 

[AnimatedGIF]

I'm not 100% sure, but would raising the temp bring CO2 out of solution, and that be responsible for the blow-off activity? Air lock/blow off activity is not a suitable proxy for pace of fermentation.

 

[phildo79]

Ah bugger. I hope that is not the case but would explain it. I used plenty of US-05 yeast, so not sure why it stuck.

 

[phettebs]

How long has it been in primary? I brewed one 3 months ago that started at 1.105 and finished at 1.025.

 

[phildo79]

How long has it been in primary? I brewed one 3 months ago that started at 1.105 and finished at 1.025.

Ten days but it got down to 1.030 after about five days.

 

[phettebs]

A big beer like that, I leave 3-4 weeks in the primary. I try to warm it up and sometimes shake the closed FV around to rouse the yeast back up. Getting to 1.017 might be a stretch with that one. Have you brewed it before and gotten it down to that?

 

[phildo79]

Never brewed it before. Come to think of it, every time I have brewed a 10% beer, I always came up a little short.

 

[phettebs]

10% beers are a lot of work for the yeast! With all of the caramal and roasted malts in an impy stout, you would expect to have more unfermentables than say a double IPA of the same strength. Strong dark beers tend to finish higher for me.

 

[Scottyburto]

I may be barking up the wrong tree but would some amylase help or is that something to use prior to fermentation. Or is it something that would strip the body too much and leave it too dry?

 

[jayk34]

Did the mash temperature creep up high at any time. I had a dry stout finish at 1.018 as I believed I was mashing at 67/68°C when in fact my thermometer was 4°C to high and I was mashing at 71/72°C.

 

[phildo79]

I may be barking up the wrong tree but would some amylase help or is that something to use prior to fermentation. Or is it something that would strip the body too much and leave it too dry?

I tried amylase before, with a stuck fermentation. It did nothing.

 

[phildo79]

Did the mash temperature creep up high at any time. I had a dry stout finish at 1.018 as I believed I was mashing at 67/68°C when in fact my thermometer was 4°C to high and I was mashing at 71/72°C.

No mash involved. It was a partial.

 

[phildo79]

So I took away the heat belt about 24 hours ago and the temp is now about 22 degrees. The blow-off tube is still producing bubbles at a rate of about every 45 seconds. The gravity is still 1.030. I fear this is as good as I am going to get. I will try some amylase but don't hold out much hope after my last experience with it.

 

[phildo79]

Update: I added some amylase and it did eff all. For some reason, the bubbles coming from the blow-off tube started behaving odd. Instead of one bubble every 45 seconds, there would be a rapid succession of bubbles every minute. Needless to say, this made me think fermentation had started again. Imagine my disappointment.

So I just kegged it. Perhaps the addition of bourbon to the serving keg will kickstart it but I am beyond giving two effs anymore. Just looking forward to trying it in August.