Harvested yeast still fermenting?

[karlos_1984]

I bottled yesterday, the beer had an OG of 1052 and FG of 1016 using 1 pack of rehydrated US-05 yeast.

After bottling I did the usual, dumped 1 ltr of preboiled and cooled water in, swished trub around and transferred to a mason jar.

I've kept an eye on the yeast and I'm wondering if it's started fermenting in the jar again. 

As it's settled, in starting to see little balls/clunps of yeast rising to the top, then sliding down the outside of the jar. I've swished it around again once more and let it re-settle but it's doing it again. 

Haven't had this happen before. There's also no clear line separating the actual yeast and trub. In the past it's usually quite easy to define between the 2. 

Anyone else able to explain this? Just concerned I may have some bottle bombs on the way. 

The SG was stable for 2 days, so I dry hopped for a week in chux cloth, then cold crashed for 3 days prior to bottling.

[Shamus O'Sean]

Hey K

Mason jar in the fridge?

Your FG looks a little high, so maybe not completely fermented out.  However, you gave it every chance: Stable for two days, dry hop for a week after before cold crashing.

What are the three things that yeast need again? Food, warmth and oxygen, I think.  If the yeast has been stable for a while and get one of these triggers all of a sudden, I suppose they could take off, but I reckon without the other two they would settle back down again.

Maybe the cooled water, if it was warmer than the cold crashed yeast, has caused some renewed activity.

I have had yeast volcanoes when I have taken out the mason jar on brew day and left it on the bench to warm the yeast before pitching.  I do not do this any more though, since Otto's advice to pitch straight from the fridge into the wort.

[karlos_1984]

I thought it was a bit high, but it didn't budge at all after that length of time. I kept it at a constant 18 degrees throughout fermentation and dry hop. I rarely raise the temp to 21 like some suggest but I've found it isn't needed most of the time. 

The jar is just on the kitchen bench. 

I've tipped the water out tonight and added another litre of preboiled water. See if this cleans it up a bit. I have washed yeast with 2 separate portions of water before to remove darker wort and that's turned out. Hopefully my beer isn't underdone and too sweet as this is my first attempt at an all grain biab. 

The figures I put into an online calculator estimated a FG of 1014 so I figured it was close enough to the mark. 

[Otto Von Blotto]

The recipe and mash temp would give an idea what the FG should be. 

I don't know if I've had harvested yeast keep fermenting, but I simply leave the mason jar lids slightly loose so if they do, the gas doesn't build up pressure. I'm obviously harvesting from starters though, not batches. Straight into the fridge regardless. Other than those potential bottle bombs it's nothing to worry about. 

Edited September 15, 2019 by Otto Von Blotto

[The Captain!!]

I have once placed a sloppy slurry in a bottle and capped it to see what would happen. Placed it in the fridge and after two months it was definitely carbonated as the pssst as I opened the cap to place in a beer. 

And yes, I degassed the beer before I capped it