View Full Version : Help with slowed fermentation

11-06-2013, 12:45 PM
Hey all,

I'm a first time fermenter and mead maker. My first batch started out with a bang, but seems to have slowed to a crawl. Any help on how to get this across the finish line would be much appreciated!

The Recipe:

About 4.1 pounds of tupelo honey
Fresh Pacific Northwest spring water (boiled then cooled)
1.2 g DV-10 yeast (rehydrated w/ 1.5 g GoFerm)
Enough water to make 1 gallon

I used the "no heat" method - i.e., I did not heat the honey or must for sanitation purposes. I gently heated the honey in a warm water bath to facilitate easy pouring. I boiled the must water first, then cooled to about 80oF at yeast pitching.

I added about 0.5 g each of DAP and FermaidK after yeast pitching, and oxygenated with pure O2.

SG = 1.149
TG = 1.006

The airlock was bubbling within a few hours of yeast pitching.
Fermentation temperature has been held constant at 64.5-67oF.

1 day after pitching: Added about 1 g each of DAP and FermaidK, and oxygenated with pure O2.
5 days after pitching: Airlock bubbling once every 4-5 seconds. SG = 1.103; pH = 3.7. Added about 0.8 g each of DAP and FermaidK, and oxygenated w/ pure O2. Adjusted pH to 4.1 w/ CaCO3
15 days after pitching: Airlock bubbling has slowed from 5 seconds to 17 seconds. SG = 1.062. pH = 3.8.
24 days after pitching: Airlock bubbling has slowed from 20 seconds to over a minute. SG = 1.041. pH = 3.8.

The 24 day mark was yesterday. I'm only about 75% of the way to my TG, but, as you can see, fermentation has slowed to crawl. There's a thin layer of lees on the bottom. There's no off odors or flavors to suggest an infection. Maybe a mild hint of a dirty sock or rubber smell, but my wife has a much better nose than I and she couldn't smell anything afoul, so maybe it was my imagination.

Based on the gravity readings, I'm at about 14.13% ABV. The DV-10 yeast I used should go to 18%. Since the pH looks fine and I seem to have added enough nutrients, I'm wondering if maybe I didn't oxygenate enough.

I'm thinking I should at the very least oxygenate. Should I do this? Should I add more nutrients as well? Or should I just do nothing and be patient?

Thanks so much for your help!!

Marshmallow Blue
11-06-2013, 01:38 PM
A SG of 1.149 creates a very stressful environment for yeast.

It's too late to oxygenate.

It's slowing down sure, but it hasn't stopped yet. Just let it go. Check the gravity in a month. And welcome to GOTMead?!

11-06-2013, 03:06 PM
Can't work it out off the top of my head but I suspect you're short on nutrient.

At this stage Fermaidk/DAP won't help. Ideally FermaidO, but failing that some yeast hulls or some boiled bread yeast (or microwaved). A couple of teaspoons in a couple of ounces of water, either simmered for a couple of minutes or zapped, either should kill the bread yeast, which is then cooled to room temp before adding. .....

11-06-2013, 04:12 PM
Thanks Marshmallow and fatbloke for your replies!

Marshmallow - about the O2. You say it's too late to oxygenate. Why? Is it just that it won't do any good now (yeast are beyond the point where O2 is beneficial), or could the O2 actually damage the fermenting mead in some way?

Thanks again!!

Medsen Fey
11-07-2013, 12:18 AM
The O2 probably won't harm anything as long as there are still active yeast, but the benefit of aeration ( as well as nutrients, pH adjustments, etc.) is greatest early on in the process before it gets stuck (or sluggish). Your nutrient plan was light - the kind of plan that will work great for a 13% ABV mead, but not what you need for a high-gravity must. Using 50-75% more would have been better.

At this point, treating with yeast hulls 1-2 g might be helpful, or using some Fermaid O. You might also let it warm up a few degrees.

Endeavor to persevere!

11-07-2013, 02:46 AM
Thanks Medsen. I'll see about throwing in some yeast hulls or FermaidO sometime within the next few days and see how it goes.

Is there any table or other reference that shows recommended nutrient amounts for various must starting gravities?

Thanks alot for the help!!

11-07-2013, 01:39 PM
I wonder if the problem is in the actual ABV rather than a lack of nutrient. If your starting gravity was around 1.150 and your gravity today is 1.006 your ABV is about 19% . What is your yeast's tolerance for alcohol?

Marshmallow Blue
11-07-2013, 03:21 PM
1.006 is his Target gravity, Its Currently stuck around 1.041 I believe. Did you check it again over these past couple days to see if it dropped below 1.041?

11-08-2013, 02:35 AM
You have it right MB, 1.006 is the target gravity, original gravity was 1.149, and as of Tuesday gravity was at 1.041 after 24 days in the fermenter. I've not taken any readings since then. I'm going to grab one tomorrow or Saturday to see what's progressing. Stay tuned!

In the meantime, I've got some Fermaid O on the way that'll be here on Saturday, at which time I'll promptly add.

Alcohol tolerance of the DV-10 yeast I used is supposedly 18%.

Thanks again to everyone who has provided input and advice - it is much appreciated!! :)

11-10-2013, 11:10 PM
Checked the gravity today - it was 1.032. Some progress since last measurement 5 days ago (1.041), but still pretty slow. Four days ago I bumped up the temp a little bit to 66-68oF.

pH today was about 3.6-3.7, which was a drop from 3.9 five days ago. Is this much of a drop normal? I should note that I'm measuring with pH strips, not a digital meter, and my ability to accurately match up the colors is probably a bit lacking.

Went ahead and added 1.5 g of Fermaid O to the 1 gallon of must today. Does this sound like enough?


Medsen Fey
11-11-2013, 07:02 AM
Using 1.5g is a good start. It is slow, but it is still moving so give it a gentle swirl a couple of times a day to keep the yeast in suspension. Then just give it time.

11-19-2013, 02:16 PM
It's been 9 days since I added the 1.5 g of Fermaid O. SG has continued to drop (albeit slowly) from 1.032 to 1.023, a drop of 0.009 points. Sitting at about 16.23% ABV right now (the DV10 yeast I used should go to 18%). Today is day 36 of fermentation.

I can't say for certain, but the Fermaid O didn't really seem to alter the rate of fermentation at all. That said, I'm open to adding more if it might be doing some good.

Would it be ok to add some more Fermaid O? I don't want to overdo it (is there such a thing w/ FO?). So far, this one-gallon batch has:

2.3 g DAP
2.3 g Fermaid K
1.5 g of Fermaid O
1.5 g GoFerm

If I add more Fermiad O, might it help at all? Would I run the risk of imparting any off-flavors? How much Fermaid O is too much?

Thanks again! You folks are great!! :)

Medsen Fey
11-21-2013, 05:57 PM
You are a little light on the nutrients for a high gravity batch. While it is possible to overdo it with nutrients, you aren't even close. You can add another 5g of Fermaid O without problem and it may help things along. It can be difficult to get past 17% with any yeast.

Did you bring the temp up?


11-21-2013, 07:28 PM
Thanks Medsen. Brought the temp up just a little to 66-68oF. I'm reluctant to bump it up too much - I've read that temps in the lower to mid range of the yeast generally produce a better tasting final product while minimizing need to age. I don't know what the hell I'm doing yet, so the best I can do is go on what I read and what others tell me. It sure is fun learning this stuff, though. Wish I would've started making mead a long time ago!! But I digress... For now I'll add some more Ferm O and see how it goes. Thanks a ton for the advice!!

Medsen Fey
11-21-2013, 10:01 PM
At this stage of fermentation, raising the temp will not hurt it and you could go ahead and bring it up to 70F.