Odd fermentation... Advice

[chesl73]

Hey guys

I was trying out a new IPA recipe and decided to do a smaller batch of about 14 to 15L. In my mind my small fermenter was 20L but when I went to transfer to it I realised it was only 15L! I had a slurry of US05 from a previous brew and I created a small starter just to check it was ok, which it was. I pitched it but I'm now at 14.5L in a 15L fermenter. After 24 hours or so the krausen kicked in and it spewed out of my air lock for a few days. I cleaned up as best I could. After about 5 days I took a measurement and the SG was still 1.029. Day 6 it was 1.024, day 7 1.019 and now day 8 it is 1.016.
Fermentation temperature initially set at 18, after 3 days went to 20, last 3 days at 21.
Is it a bit odd that the fermentation is taking so long? I don't recall having it take this long before.
Attached is a picture of the fermentation this morning, does it seem strange it looks like this after 8 days?

 

[garage_life]

Could have lost some cell count through the blow off? What was the OG?

 

[philrob]

Looks like a truckload of yeast on top.
How are you measuring your SG? Refractometer or hydro? And where do you take your sample from? If from the tap, is it clear beer, rather than heavy with trub and yeast?

 

[chesl73]

OG was 1.060.
It was quite a bit of thick yeast slurry I used initially. It is a thick top layer, I was thinking it would be settling out by now. I did lose some yeast from the blow out but as the picture shows it looks like there's plenty left. The picture attached shows a sample of the beer taken from the tap which looks good and tastes good.

 

[chesl73]

Sorry, to answer your other questions... Sample is always taken from the bottom tap. Measurement via refractometer however the 1.019 measurement was with a hydro

 

[MHB]

When you have a question about yeast, one of the first things to look at (before you panic) is your apparent attenuation (AA%). Starting at 1.060, down to 1.016, (just use points) 60-16=44, 44/60*100=73%.
US-05 is a medium attenuator, usually pulls up around 73-75% AA.
So relax, your on track.
Mark

PS
Just noticed your comment on using a Refractometer
Unless you understand the maths, you cant use one after you start the ferment.
Refractometers measure how far the sugar content bends light, its a direct relationship, more sugar more bend.
Once you start to form alcohol you are into a 3 component problem with Water, Sugar and Alcohol that all bend light (refractive index, RI) different amounts, gets pretty complicated to tell what is causing a given amount of bending.
With the OG (original RI) you can interpolate the amount of alcohol and the present gravity, do a search for some software that will do the calculation.
M

 

[chesl73]

Yes, I understand the issue of refractometer measurements in fermenting wort. I interpolate.
I'm getting to my FG just slowly, just never taken this long before and the yeast has normally settled out by now so that was what I found curious.

 

[MHB]

Is that a Leute, footless glass?
Always thought you were on a mission when you choose a glass you cant put down.

Probably has more to do with the average of the yeast cells in the culture, storing slurry for any time can cause changes to the population and lead to some unexpected results.
Naturally the number of viable cells, the amount of O2 available, protein content of the wort.... lots of things can affect a ferment. still if you are getting on toward your expected FG in les than a week it probably isn't too much of a worry.
I have has a few US-05 ferments that had a really greasy looking head, two things that appear to contribute to that and excess foaming have been in my experience are - Fine malt flour from a badly separated hot break, mostly an issue for BIAB brewers - Incomplete conversion (a blue brew) mash not finishing converting all the starch.
Might be worth having a look at your processes if the problem persists.
Mark

 

[chesl73]

Thanks for the replies. Will just wait and give it time, it'll be alright in the end