Longer than usual fermentation time??

[Brewmerang]

Hello fellow brewers
I currently have a brew in the fermenter which has taken almost twice as long to reach FG (after lag period) than it should. I'm hoping someone here might know why. Has any one else had a similar experience?
Here is my recipe.

I used 1 packet of Fermentis US-05 sprinkled (not rehydrated) onto 25L of wort at 18.5°C. This was an intentional under pitch, and as expected, there was a long lag period- about 20 hours. I read that US-05 can be sluggish, taking up to 24Hrs to take off even when pitched at an optimal rate at these lower temps. I have used 05 before, at higher rates, pitched at 21°C, resulting in shorter lag times and always reaching FG in about 2 days after lag. This one took four days! Almost 5 including lag time!
Info from iSpindel via Ubidots. The fermenter has remained sealed.

Calibration is not optimal. FG reads about 3 points lower than actual.
The yeast was well in date (3/2024), kept refrigerated and brought up to 19°C before opening the pack.
The lag time is not the issue for me. It's just that I have never seen such a slow fermentation and I can't seem to find any info on why this has occurred. I will, of course, know how it turned out when it comes time to taste it.

Am I worrying about nothing? Or could there be an issue that I have overlooked? Any ideas?

 

[DJ_L3ThAL]

I wouldn't be worried at all, any ferment that can complete in 4-5 days is still a very healthy ferment. You intentionally under-pitched also so you have the smoking gun in your hand.

 

[Jens-Kristian]

Reaching FG in 4-5 days is pretty fast for any brew, I'd think. I've never used that particular yeast but I usually don't bother thinking about FG until a week in.

 

[philrob]

Given the underpitch of 1 packet of US05 in 25 litres of wort, I think 4 days to FG is entirely reasonable.
I don't see there is anything of concern here.

 

[Brewmerang]

Thanks for the helpful, reassuring input guys.
It actually took about 7 days in total to reach FG, and it seems to have turned out great.
I tasted it when bottling and I reckon that this could be one of my best.
The hops schedule was pure experimentation, but it worked well.

 

[yankinoz]

We often treat panic attacks. "Help, my fg is too high" is the most common cause. So you're in good company. Persevere, keep brewing, drink.

Thanks for the helpful, reassuring input guys.
It actually took about 7 days in total to reach FG, and it seems to have turned out great.
I tasted it when bottling and I reckon that this could be one of my best.
The hops schedule was pure experimentation, but it worked well.