fermentation not completeing

[tipsea1]

it seems to me im missing the boat somewhere,i cant get a simple sugar wash to go to completion.Test wash;5 gallon water,10lb sugar,mixed well and sitting at 90f.I rehydrate two level teaspoons of dadys distiller yeast and make sure its happy.Verify water temp to yeast manufacturers temp,make sure ph is in range,get a sg reading,add nutrient pour in yeast.Instal high flow airlock an set fermenter in a climate controlled cache. First 3 days all is good,by day 5 it has slowed to a bubble every 10 seconds,day 7 about the same maybe slightly slower.Take a sample to test fg,its only produced 6% abv,and the most ive gotten so far is 11%abv on a 20% potential run,and im using the potential abv number only because i dont have the sg scale memorized yet.I assumed it was a nutrient problem so ran some turbo 48 yeast as a comparison test and it was almost the same 6% in 5 days.So im thinking now im killing the yeast some kind of way,, any suggestions or tweaks in my process,even as simple as it is.

[dstaines]

That actually sounds about right.

Table sugar adds 46 gravity points per lb/gal. (1lb sugar + 1 gal H20 --> 1.046 SG). With two lb/gal of sugar, your gravity should have been 1.096. Taking that gravity all the way down to 0.990 yields about 13% abv, so 11% isn't too far off. Keep in mind that the number of bubbles per minute is a fairly useless measure of when a fermentation is done, as is the number of days in the fermenter, because it says nothing about what actually going on *in the fermenter*.The only meaningful measurement is the specific gravity. If your hydrometer reads more than 1.000 on a sugar wash, it's not completely done fermenting to dryness.

Sugar washes can be trickier than they seem, and sometimes take a long time. Patience is your friend. Yeast are not evolved to live off of processed sugar, so they need some hand-holding to get the job done without stressing them out, killing them, or putting them to sleep. It sounds like you're on the right track with adding nutrients and adjusting the pH. Did you aerate the wash well before pitching? I didn't see that in your process description and it is an important step for building a large enough colony to ferment completely dry.

Tell me about your fermentation temperature controlled cache? Yeast give off heat as a byproduct of metabolism, and you may be getting them too hot. Temperature in the fermenter can be 10+ degrees higher than ambient.

The best tip though might be to set your sights a little lower. Yeast get poisoned by the alcohol they excrete, so backing off some on the sugar will help them out. You will also produce a better tasting spirit because the yeast will produce less off-flavors.

[bellybuster]

you will have a hard time here getting anyone to help you get high gravity washes going. It is believed by the masses through experience that anything over 10-11% is pushing the limits and produces crap drink.

That said, sugar should ferment dry without issue. Only issue I have ever encountered with sugar is ph dropping too low. You haven't mentioned the ph on your finished washes.
Also, how do you judge that they are finished fermenting? I can tell you for certain that uninvited sugar takes quite a bit longer than inverted sugar.
Climate controlled cache? what temp are you fermenting at?
posting same time as dstaines

[S-Cackalacky]

You said you took a final gravity, but you didn't say what it was. If it's 1.000 or below, it's finished. What was the original gravity? That's where you determine the potential ABV. Also, it might help to assure success if you use a recipe from the "Tried and True Recipes" section of the forums. Those recipes have been successfully made by many members here.

Posted while Bellybuster was posting.

[dstaines]

Bellybuster has a good point that I forgot. If you invert the sugar first it makes it a lot easier for the yeast to metabolize. Inverting breaks the sucrose molecules in half, so there's less work for the yeast to do.

[bellybuster]

Bellybuster has a good point that I forgot. If you invert the sugar first it makes it a lot easier for the yeast to metabolize. Inverting breaks the sucrose molecules in half, so there's less work for the yeast to do.

true, although I never do it myself, I have time though. I have sugar washes that take a couple weeks to ferment dry. I also ferment allot cooler than most.

[shadylane]

it seems to me im missing the boat somewhere,i cant get a simple sugar wash to go to completion, any suggestions or tweaks in my process,even as simple as it is.

Use less sugar.

[T-Pee]

What's the pH? With that much sugar I can't imagine it not crashing.

tp

[whistlewetter]

I also agree that you should start with a lower SG. I have not tried inverting the sugar but I may give that a shot next time!

[shadylane]

There's very little to buffer the pH on a sugar wash and it's prone to crashing. Especially on high gravity washes.
Pushing yeast to the max is a fun experiment but it makes for fermentation problems and an inferior shine.

[CH3CH2OH]

For the yeast you are using I agree that you are using too much sugar. Why be so greedy? 10% is max for anything that will finish in a week-10 days with regular type yeast, ONLY COMMENT ON TURBO YEASTS >>>>>>>>>>good for fuel

Most yeast can't handle the stress of that high of alcohol% and will create a lot of off tastes in the process as it dies out.

If you want a higher SG wash to ferment out clean, use a specialty yeast like Uvaferm 43. If you rehydrate it properly it can easily get a 14% wash to ferment dry with no off tastes but it will take 3-4 weeks and you need to keep it 20-24'C or 68-75'F

inverting sugar isn't worth the time, mess and effort to do it.

[tipsea1]

Thanks to everyone so far that's replied with sound advice,its not that I'm trying to be greedy an push the yeast too far,I was wanting to be sure I was in the ball park.I see now that I am,,I'm sure it is crashing also because I have yet to get an where close to a zero fg reading.I'm going to readjust an bring the sugar down to a 12% potential an see if I can get it to finish

[tipsea1]

my targeted fermentation temp when using dadys distiller yeast is 90f,I can only assume this is rite its what I have read.My cache is quite simple,its a chest freezer that I gutted down to only the box an lid.The ambient temp is controlled by a basic heating blanket laided down the walls an across the floor,it took quite a few test runs but made a chart of the temp in relation to the numbers on the heat selection dial.I deal with the thermal run away by running a dual input solo controller,it monitors vessel an ambient temp,if vessel temp goes plus 2degrees of setpoint it will shut blanket down an start a muffin fan.Summer temps are much easier due to the fact that its subsurface.

[CH3CH2OH]

Sorry, I shouldn't have insinuated greed as your motivation. I assumed from your post that because you were using a high abv commercial distillers yeast and a potential abv of 20% fermenting it at a high temp that getting a high % in a short time was your goal.

One thing to consider is that what final spirit you are fermenting for may determine what temp you should ferment at

Hight temp fast ferments are great for something like rum where you want some of those funky kind of flavors to carry over to your final product

Neutrals, where you do not want funky flavors, dont do so well with a hot fast ferment

You have to remember that a commercial distillers yeast may be great for a distillery that is trying to up the abv and barrel aging a whiskey for several years. This allows the barrel to positively change the flavor profile and the angels have the time to do their work. Most of us try to start with a tried and true recipe with a suited yeast and guage for around 10% for flavored spirits because we dont have the luxury of many years in the barrel to fix things!!

I suggest having a go at the tried and true recipes and you will have much more success and be way happier with the process and your final products.

Cheers