Fermentation Appeared Done, Then Restarted

[James_AZ]

I’m fermenting an English Ale in a Unitank. I have a RAPT Pill in the tank. The Pill is not calibrated.
OG was 1057 pitched Wyeast 1099
After about 36 hours the SG flattened out 1017 according to the Pill. Temp settled to 71.5F Stayed there for 12ish days. At that point I closed the blow of valve and put 5psi of CO2 in the tank and dumped yeast. 12 hours later (next morning) I noticed the temp had risen to 73F and pressure in the tank was 7psi (what my spunding valve is set for). I checked the RAPT portal and the SG had dropped slightly. 3 days later the Pill is measuring 1012 and it hasn’t leveled off. I’m guessing dumping the yeast stirred it up and restarted fermentation? Any Ideas what’s going on?

Here’s the first couple weeks up to the yeast dumb:

Here’s since:

 

[hotbeer]

Probably some more fermentation going on unless it was just your Pill being buoyed up by crud that slowly started coming off of it as the beer cleared.

There is always the possibility that you got a infection when you dumped the trub. Either by the cleanliness of the parts of the valve that briefly got exposed or any air being drawn in.

What was the predicted FG and had your Pill been accurately reporting the FG's of other batches? Or do you not double check the FG with a typical hydrometer before bottling or kegging?

More complex sugars can take longer for yeasts to consume. I'm not sure how long a time gap it might be for yeast to go from chomping on the easy stuff to chomping on the other sugars or if they even do one before the other.

Don't worry about it though. Just wait till after it's bottled/kegged and conditioned. You won't likely easily change anything about it even if you knew for certain that something bad is happening.

 

[James_AZ]

Beersmith estimates FG 1017. My last batch finished there. Guess time will tell.

I haven’t used the Pill in a while, I usually calibrate it before dropping it in, and didn’t this time. Screwing and unsccrewing it to charge the battery apparently can cause it to be off. My. refracctometer said 1057 for OG and the Pill measured 1050, so seems the pill is a little low.

 

[ncbrewer]

If bottling, I would definitely wait until gravity is stable. Taking gravity samples would be an option to be sure.