View Full Version : Stuck fermentation or am I done?

02-20-2006, 04:07 PM

I have 2 5 gal batches going. 1 is 5 weeks old that started out at 23.4 brix and for the last week has been sitting at around 9 with a sluggish fermentation. The other is 3 weeks old and started at 24.6 and was slowing down as well. About a blip every 15-20 seconds. Its brix was 17ish. Just got a PH meter and because the fermentation was a little sluggish I took a reading from both. The 5 week old was 3.2 and the 3 week old batch was 2.9. I adjusted both up to about 3.8 as Schramm says to do. I also added a little nutrient and whriled a bit of each must in a blender for some O2 hopping to pick up the ferment. Well the younger one started right back up again with a blip every 4 seconds or so but the first one is quiet with nary a blip or a blip every few miniutes(more of a weak burbble).

I am worried about the first one because I pitchedwith WhiteLabs 720 it says it should attenuate to 75% with an alc tolerence of 15%. Well, I am way below that and only has attenuated about 65%ish and it hasnt started back up like its younger brother. Should I pitch new yeasties and try to ferment out or should I just rack and wait?


Edit: This one ties in with my earlier post.

02-20-2006, 08:29 PM
White Labs Sweet Mead yeast. That one has given me lots of trouble. If you don't have absolutely perfect conditions up front: good ph, good nutrients, aerate like crazy, give it a good stirring for the first 3 to 5 days - it's going to have problems.

Sounds like you are using Ken's Troubleshooting Problem Fermentation's section. Be careful when you aerate a fermentation that has been stuck a long time - you risk Oxydation.

Last time I used White Labs 720 and it stuck, I pitched a new vial in a starter of honey, water, and nutrients (aerate, aerate, aerate), and slowly added the old batch into the new starter in 1 gallon increments. Note it never fully fermented to my satisfaction, I ended up with a very sweet mead around 7- 8 brix.

02-20-2006, 08:38 PM
Adjusting the pH is a good thing to do. Adding nutrient late in the game really is not much help if at all.

What you're describing is exactly what let me to stop using liquid yeast in meads. I just don't like them for mead. The sweet mead yeast has, in my opinion never been consistant in my meads, even when I pitched into parallel batches (same bulk must divided into three 6 gallon batches) the results were all over the map, and two out of the three had very sluggish fermentations. So I stopped using them a while ago.



02-21-2006, 01:51 PM
Sounds like I've been lucky. My best meads have been with the sweet mead liquid yeast, and they've been consistent. My only troubled batch was with a fresh pack of dried yeast. I don't remember exactly which strain, but I made a starter and everthing. I still don't know what happened with it. No matter what I did, it wouldn't go. I ended up making a similar batch of super dry and mixing it - with very good results in the end.

I'm not calibrated on brix, but if it is truly dead, then you might want to think about blending with a dry like I did.

02-21-2006, 06:41 PM
Thanks all,

The wl720 batch has just been sitting there for a while doing nothing ... Ill take a reading tonight and if it still is at 9 brix I am thinking about adding a satchet of red star cuvee. Does this sound OK or should I still wait?


03-30-2006, 12:03 AM
So I am not the only one struggling with 720. I really like this yeast, I have used it on my last 5 or 6 batches and I have noticed the inconsistencies also. My last two batches I was attributing the problems to the cooler tempratures, I wasn't sure how close it was to being done by the time my basement got down to 50 degrees. But after going over my notes I have noticed many different results. I'm not ready to give up on it yet. I still have another vial in the fridge and plan on over pitching a bit on the next batch.

richard lambert
04-01-2006, 09:11 PM
I just use the same yeast on my 5 gal. It was stuck for a week. Our friends @ the forum told me to check the temp. has to be between 70 to 75. I use an electric blanket and I aerateed for 3 days and it started right up, one blip per minute. Now if they don't like the 720 what sweet wine yeast do they suggest for next batch?

04-02-2006, 12:35 AM
Howdy Richard,

ANY yeast can be a sweet mead yeast if the initial brix/gravity has a potential alcohol by volume greater than the alcohol tolerance of the yeast.

For example, K1-V has an ABV tolerance of 18% if you mix up a must with an initial brix/gravity of anything less than 31/1.132 (about 18 lbs of honey in a 5 gallon batch) your mead will end up dry. This is because the PABV of the must is about 17.93%. Since K1-V will tolerate up to 18% ABV it will take the must to dryness. Caveat: This is is most cases, sometimes due to temperatures outside optimal fermenatation ranges, poorly managed primary fermentation, nutrient starved musts, chemical interference (ingredients with sorbates or sulfites) and other variables, the yeast can stop before it reached it's tolerance level. I hesitate to call this attenuation because I was chided once by Clayton Cone at Lallemand for using that term. Not in a bad way, just in a matter of fact way.

OK, second example of K1-V: Now suppose that must you mix up has an initital brix/gravity of a little over 35.5/1.154 with a PABV of about 21%. K1-V will ferment to completeness at about 18% ABV and leave some residual sugar and a sweeter mead. Same Caveat: This is is most cases, sometimes due to temperatures outside optimal fermenatation ranges, runaway primary fermentation, musts that are dosed over recommended levels with nutrient, step feeding and other variables, the yeast can keep going and surpass it's normal tolerance level and leave your must dry.

So again, any yeast can be a sweet mead yeast if the initial brix is high enough to be above the ABV tolerance of the yeast; and any yeast can be a dry mead yeast (including the sweet mead yeast you use) if the ABV is below the tolerance of the yeast you're going to use in your must.


Here are some links to help you in your quest for yeast knowledge:

Mead calculator (plug in your honey amount and desired volume to check your must's PABV level):


Lallemand Wine Yeast Reference Chart:

Lallemand Wine Yeast Strain Descriptions:

White Labs:

LeSaffre wine yeast selection chart:

LeSaffre (Red Star and Springer Oenologie) wine yeast strain selection list:


Jack Keller's Winemaking Yeast Strains Page:

Winemaker's Magazine Yeast Strain Reference Chart:

More Beer and More Wine Yeasts for sale page (They have 73 strains for purchase, and it is where I get all of my yeasts):

If you need more than that come back and lemme know!



richard lambert
04-03-2006, 03:06 PM
Oskaar,Thanks for the info.it seems to me thet the KV1 1116 is fail safe. By the way after two weeks I checked out the my batch and was very pleased with taste,acid and the 5% abv@ this time in the must. what is strange is that I am obsesed with the mead and total enjoy watching and pampering the baby. Oh well thanks again and I sure I will be back on for racking and bottling for your expertise. Richard