question about re-pitching

[burntchef]

So this batch is on day 14 of fermentation. og was 1.060 gravity now is 1.030. That should yield a 3.9 abv or there about. fermentation was done at 65-72 with wyoo7. If I do not have a gravity change in the next couple of days, what happens if I re-pitch to determine if I am leaving fermentable sugar behind? The thought being if it re-starts vigorously I have a yeast issue, if it does not re-start I have a mash issue. What do you think?
Eric

 

[RPh_Guy]

fermentation was done at 65-72 with wyoo7.

Huh?

What causes a stuck fermentation?
1. Unfermentable wort.
2. Temperature extremes / fluctuation. This includes temperature shock from rehydration or starters.
3. Poor yeast health -- low nutrient and/or low pitch rate and/or low aeration and/or osmotic shock (high OG) and/or inadequate trace elements. Yeast-dependent.
4. Wild killer yeast.
5. Highly flocculant yeast.
6. High alcohol level.
7. Refractometer vs hydrometer reading misinterpretation, poorly calibrated instruments, or other measurement error.
8. Adding preservatives or other substance toxic/stressful to yeast.

Repitching the same yeast will help with 2, 3, & 5.

 

[burntchef]

Thank you for the reply!
I can rule out 4,6,7,8,.
Repitching will help with 2,3,5,
That leaves 1 as the burning question
I am going to repitch to satisfy my curiosity, then I will know if 1. is my issue.
thanx
Eric

 

[Cavpilot2000]

I would find it HIGHLY unlikely that you have 1.030 worth of unfermentable wort, I don't care how badly you might have mucked up the mash. If you screwed it up THAT badly, you would know it (your mashed at 170F instead of 150F, etc.). There's no way some little screw up that would have escaped your notice produced 30 points of unfermentable wort.

 

[RPh_Guy]

I would find it HIGHLY unlikely that you have 1.030 worth of unfermentable wort, I don't care how badly you might have mucked up the mash. If you screwed it up THAT badly, you would know it (your mashed at 170F instead of 150F, etc.). There's no way some little screw up that would have escaped your notice produced 30 points of unfermentable wort.

Poorly calibrated thermometer?

 

[burntchef]

Thermometer calibrated, check. Mash temp check. Hydrometer checked in water, check. 30 points left on the table, prolly. I have a starter working now and when it is ready I am going to pitch.
Eric

 

[burntchef]

So I repitched the starter and got no action in the fermenter. Waited 7 days and kegged up a muddy mess. I am calling this batch " deep tannins ". After a lot of thought and reflection I ditched all my yeast.
Batch number 8 is in the fermenter now. I pitched s-04 on wort that was 1.061. It bubbled for 12 days straight and stalled. The gravity was 1.020. I warmed the wort and gave it a vigorous stir and it re started. It is now day 14 and still going. I can only conclude that my yeast was the issue. Can not wait to see where I end up and taste.
Eric

 

[Cavpilot2000]

Weird. I usually keep a few packets of dry yeast (34/70 for lagers and S-05 for ales) on hand in case of a stalled ferment. I just pitch them dry and usually they will do the job of finishing up.