Decrease in fermentation rate

[ProblemChild]

Hi all-
Been experiencing a bit of anomaly lately. My fermentations have slowed down considerably. I eventually hit gravity, but the time it takes to get there has been very slow in the past few months.
At first, I thought it may be the yeast I was collecting. WY1968 started taking about 16 days to get to FG and I was used to half that. That seemed odd to me. The next batch I ran, I decided to use WY1056. Should be almost there inside of five days with maybe a week of clean up. Nope – still took well over two weeks.

Since the batch before that became a casualty of a bad gasket on the keg, I ran the same recipe again with fresh WY1968. Again – 16 days. This batch was followed with a DIPA and Imperial A38. Took three weeks for the krausen to fall and hit gravity. Now I am using WY1725 and after 10 days I am at 1.024SG and still have moderate krausen and airlock is plinking every 10 seconds or so.

What gives? Ambient is 63 in the room where I am fermenting for the first few days and I move it to 68 degrees after that. Mty process is fairly steady and there have been no changes and I have not had any infection I could detect.

Any clue what would slow things down like that? Granted, my results as of late have been wonderful, so no worries about quality – just seems odd that this would start happening

 

[Pappers_]

I don't think two or three weeks is unusual, in my experience. If I'm doing small, sessionable beers, 7-10 days is more normal. Just my experience.

As for why you've experienced that change, there must be an explanation, but I don't have it. The good news is that you're pleased with the quality of your beers. If it isn't broken, don't try to fix it!

 

[Dcpcooks]

Grain quality, Mash temps, yeast health, pitch rate and o2 levels and fermentation temps can impact fermentability. Are you positive nothing else has changed? A three week window on a dipa isn't crazy long imo.

It sounds like your not controlling fermentation temps outside of ambient temps so that could be a variable.

 

[ProblemChild]

I don't think two or three weeks is unusual, in my experience. If I'm doing small, sessionable beers, 7-10 days is more normal. Just my experience.

As for why you've experienced that change, there must be an explanation, but I don't have it. The good news is that you're pleased with the quality of your beers. If it isn't broken, don't try to fix it!

Really not trying to manipulate anything. Happy my results have been good. Good beer, happy me.

 

[ProblemChild]

Grain quality, Mash temps, yeast health, pitch rate and o2 levels and fermentation temps can impact fermentability. Are you positive nothing else has changed? A three week window on a dipa isn't crazy long imo.

It sounds like your not controlling fermentation temps outside of ambient temps so that could be a variable.

Pretty stringent about mash temps and providing enough o2.

Curiosity is not so much because it is long, just that it is nearly 30-40% longer than it has up until about early May. Basement was cooler then and ambient was even lower than now. I thought things might scoot along a bit faster as the temps warmed up.

 

[kh54s10]

Strange. How many generations do you have on these yeasts. I have read that for a couple of generations after the original pitch the yeast is usually more active.

As a check, start with some fresh yeast and see if you get back to 5-10 days.

I have never taken gravity reading over that long a period. All but a couple of my beer seem to have finished by 10 days. I don't know exactly because I have never taken a reading before day 14. Of those almost all were at predicted FG or lower and I have bottled or kegged them. A couple of really big beers might have taken longer but I left them to age intentionally, so I didn't measure for a month or two. Another stalled and with agitation and temperature rise it finished in a few more days.

 

[ProblemChild]

Strange. How many generations do you have on these yeasts. I have read that for a couple of generations after the original pitch the yeast is usually more active.

As a check, start with some fresh yeast and see if you get back to 5-10 days.

I have never taken gravity reading over that long a period. All but a couple of my beer seem to have finished by 10 days. I don't know exactly because I have never taken a reading before day 14. Of those almost all were at predicted FG or lower and I have bottled or kegged them. A couple of really big beers might have taken longer but I left them to age intentionally, so I didn't measure for a month or two. Another stalled and with agitation and temperature rise it finished in a few more days.

My WY1968 was only on third generation. All others mentioned were first.
I normally wait until airlock has slowed to maybe a bubble at every minute or so and then take a gravity. Most batches hit this point within 5-8 days for me. I take a gravity, purge with CO2 and basically predict when to take the next reading based on current gravity. If S/B 1.010 FG and is currently 1.018, I will wait five days or so. If S/B 1.010 and is 1.012, I will take a gravity in two days.

Current porter with Thames Valley Ale is still perking at a rate of every 10 seconds at day 8. It blew up like mad within 6 hours of pitching and has been plinking along since.

 

[kh54s10]

As I don't often bottle anymore I rarely take 2 readings. Even if I am bottling, if I am within 2 points of predicted FG, I don't take a second reading. Especially if it is below predicted. As I have said I have only had a couple that went more than 2 weeks. Almost all have stopped before day 10, but I leave them all at least til day 14. On a lot of them did not take a reading until I was ready to package, through procrastination, that often being between 3 weeks and up to 5 months in primary. Still those almost all of those were done by day 14.

Again, I don't know what would be contributing to your lag in finishing other than less than really healthy yeast pitches. - I am not saying that this is happening though.