New ferm chamber. Need advice on time & temps

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ScotianHobo
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New ferm chamber. Need advice on time & temps

Post by ScotianHobo » Fri Nov 02, 2018 10:47 am

So I'm still still a bit of a NooBrewer but I've done my reading and how-to video watching and feel like I have a pretty good handle on first principles across the board.

What I'm learning about now is how to manage my process using my new whiz-bang fermentation chamber (chest freezer) with an Inkbird 310b (12 step) temp controller. I also have the Mangrove Jacks Heat Pad ready to go. More on that in a minute. My goal in modifying my process is motivated by some good brews so far in my first year of all-graining but most with a bit of off flavours that I'm more critical of than others. I know I can do better and although I know there's a lot of variables at play, I'm trying to remove temp control as one of them. So here we are.

Recipe:

I'm doing a 6G BIAB Ale using a bunch of leftover and forgotten stuff in case my new equipment beguiles and befuddles me. Hopefully I'll cry less.

Grain = 4.87kg (3.631 2 row, 228g cara pils, 908g munich, 50g oats, 50g rye)
Hops = 60m 16g Amarillo 8.6% | 45m 6g Centenial 10.3% | 25m 8g Citra 12.4% | 10m 8g Simcoe 12% | 1m 14g Citra @12.4%

I had a bunch of leftover hops and just decided to chuck em all in. Knowing that my OG on my last batch of this recipe was about 1.045 I tossed in a bit of corn sugar during the boil and sparged like a samurai (their sparge technique is a little known feature of their awesomeness, true story...) and got to a starting gravity of about 1.058.

I pitched one pack of White labs California Ale that was 20 days past it's BB date @17C and set it into the chamber at a target temp of 18, with a 0.3C cold kick in and 1.5C hot shut off. Theoretically that should mean my temp should be stable between 17.7 and 19.5.

Observations:
Day 1 (Oct 25) - Crickets. Paranoia about expired yeast and too low a temp. Action: bump up the temp range about a degree and a half.
Day 2 - More crickets. Action: procure kleenex for tears.
Day 3 - Got my head down into the ferment chamber to check temp sticker on bucket and accidentally vaped the largest single dose of CO2 i've ever experienced. Gas-induced tears from sinus trauma mixed with tears of joy.
Days 4- 7 (today) - I continued to tweak by 0.2-0.5C the set value of the temp controller to try and keep the reading at 18. The temp probe is on the (out)side of the bucket 3/4 down. A small thermometer is on the freezer "shelf" a few inches above that. A brew thermometer from Noble Grape is in a pitcher of star-san to mimic the beer temp. The probe consistently reports a temp of 17.8-18.2 per my adjustments. The small thermo reads 19. The brew thermo says 20-22 and I have found it to be an outlier during my mash measuring as well. I'm close to concluding it sucks but I have no reliable objective way of knowing "truth" so treat it like the junkie it is and keep giving it another chance to do what it says it's going to do. But I digress.

The last few batches I've done I skipped racking to a secondary. Party because I wanted to try the Coopers DIY Carbonation Drops (rock sugar) for bottle conditioning, thus making a bulk prime unnecessary and partly because I had a suspicion that I was oxidizing. I've since read from and spoken to tonnes of righteous minded folks who scoff at that and I understand there's some thoughts on all sides on that one.

I haven't done a gravity reading yet because I'm paranoid, fearful and superstitious and just don't want to frig with anything just yet. There's still activity in the air lock as well.

My questions now are:

1) How long should I expect the yeast to stay in suspension at this rate? My concern is that they'll start to finish up nd during a kick-on of the cooling will get shocked out of suspension. To counter that and as a segue to my next step:

2) I intend to allow a gradual warm up to 19, 20 etc as primary turns to secondary (irrespective of whether I do or don't rack to a carbuoy). I have not been able to find any real solid guidelines for when exactly I ought to do this, for how long or at what rate I ought to increase temps. The idea being that the temp rise = a cleaning up the beer.

3) Total time. Obviously at some point I'm going to figure out when I've hit my target. BUT- because I've never used THIS yeast, and because it was perhaps less than 100% (given that it was slightly past BB date) and because I bumped the gravity with sugar a bit and because I'm fermenting at a lower slower rate I'm not fully confident I'm going to "know" when its done and when it's time to start ramping up the temps (and for how long or by how much)

4) On that last point - I intend to use the heat pad one of two ways: either directly under the bucket or sort of suspended in the chamber. I honestly don't know which is best. Obviously whatever I do this time I'll do differently next time and see if there's a difference (all else being equal...) but does anyone have any leanred wisdon or sage advice on one route versus the other?

The room the freezer is in is in the basement and with November chills won't get above 16 or so. I don't have confidence the brew alone will produce enough heat to let it free rise much above 19 today, much less in a few days when things slow down that much more.

Based on the above does anyone have a suggested "heres what you should do for the next week/2/3"? Anyone feel passionate about me racking versus just leaving on the cake? I have a deadline of Nov 20th to remove from the chamber so I can get the Bulwark Cider kits that should be in by then in there :)

Thank you!!

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wcturnedec
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Re: New ferm chamber. Need advice on time & temps

Post by wcturnedec » Fri Nov 02, 2018 11:25 am

First things first, I'd say you underpitched your yeast even within the normal range for WLP001. When fermenting cooler, as you did, you would need a healthy and larger cell count.

Check out these two calculators:
http://www.mrmalty.com/calc/calc.html
http://www.brewunited.com/yeast_calculator.php

Do you have something to pull samples from the fermenter? Ie wine thief, turkey baster? I'd give it another couple days then pull a sample to see if the gravity has dropped.

As I mentioned above, I've fermented cooler on some ale yeasts (WLP029) but pitched a large amount of yeast and accepted that the lag time for the yeast to start doing its thing would be longer.

Hope that helps.
On tap: Wet n' Wild Amber, Coconut IPA, Sumac Saison
Fermenting: Brett Table Beer, Scotian Dubbel, Faux Schwarzbier, Tripel (2G), Topless Hefe (BS Comp), Hoppy Rye Golden Ale
Coming up: Dunkles Bock, Horchata Stout
Bottled: RIS, American Barleywine, Brett Pils
Souring: Golden Sour, Sour Wheat, Sour Saison, Sour Red

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Re: New ferm chamber. Need advice on time & temps

Post by Woody » Fri Nov 02, 2018 4:19 pm

It's a definite under pitch of yeast. It will ferment but as you noticed there will be a lag. I'm guessing your finishing gravity will be higher and you will most likely have some off flavours from unhappy yeast. A 6 month old vial of yeast will need a few steps to ferment 6 gallons of wort at 1.058. One of the above mentioned calculators will help figure that out. I'd wait it out and keep it at the same temp. After 3 weeks or so take a gravity reading and have a taste. If your happy keg it, if not it's a valuable lesson every brewer learns. :cheers:

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Re: New ferm chamber. Need advice on time & temps

Post by Woody » Fri Nov 02, 2018 4:57 pm

I should also add the fermentation chamber is a great idea and one that will help your beer turn out much better. Yeast health is just as important so I recommend getting a stir plate and flask to build up your yeast. If it's not in the budget right now maybe just buy multiple liquid yeast or use dry.

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Re: New ferm chamber. Need advice on time & temps

Post by ScotianHobo » Sun Nov 04, 2018 10:16 pm

:cheers2:
Thanks for those calculators. Saw them posted elsewhere but just dead links for me so I haven't been able to run those numbers. Kinda driving me nuts as it's a variable I'd like to understand better.

Update:
I thiefed a sample and got a reading of about 1.014 down from 1.057 nine days ago and there's still some airlock action. It also tastes really damn good! The late addition citra is really coming through which I'm quite hoppy with. ;)

Question now is a best guess on that potential underpitch you speak of. I don't mind chucking more in but I also kind of want to test the limits.

Again I have no real sense of timing on my next step. Absent any wisdom my best idea is to forget about it for another week, bump by 0.2C each day and hope for a few more points?

I'm also still undecided on racking it or leaving it. If I'm worried about dead yeast and rack too late is that just blue on black and every bit as useful an addition?

Thanks for the thoughts. Cheers.

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Re: New ferm chamber. Need advice on time & temps

Post by Woody » Mon Nov 05, 2018 1:42 am

If you are at 1.014 don't pitch any more yeast. You can warm it a bit but it's not really needed with WLP001 at those temps. I'm surprised that a liquid yeast 20 days past it's best before so 6+ months old fermented 6 gallons of 1.058 wort to 1.014. The beer gods are smiling upon you. Take that horse shoe and run. Great to hear your are happy with the beer. A starter next time is my recommendation. I only primary so I'd save the time and not rack until you bottle or keg. Take another reading around day 14 and I'm sure it will be close to finishing. I figured it would have taken longer.

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Re: New ferm chamber. Need advice on time & temps

Post by Woody » Mon Nov 05, 2018 2:22 am

If you find the links don't work google Brew United Home Brew Dad's yeast calculator. The info below I cut and paste from the site. I plugged in your numbers for the older yeast and show a 500ml starter and 1500ml starter (using a stir plate) are required to build up a cell count of 300 billons cells. Your target pitch is 243 billon cells for 6 gallons at 1.058 OG.

Assumptions used by the calculator
• Liquid yeast is assumed to lose approximately 20% of the total viable cell count per month. This figure comes from a White Labs statement that indicated that you could expect 75%-85% viability after a month; 20% is used as a middling factor. I also assume that the max viability on any package of yeast is 97%; call me a cynic, I don't see you getting 100 billion live cells unless you bring the package directly home from the yeast lab

There are multiple models out there for calculating loss of viability. If you go with a linear model (i.e. you lose 20% of the original cells per month), you end up with 0% viability after five months. I know of far too many cases of people who have brewed with yeast older than that, so I don't trust that model. Instead, I do this as a "running" total - you lose 20% in one month, 20% of the remaining balance the next month, and so on. This model has it own flaws, of course; since you are always deducting a percentage, you never get to zero cells - which obviously cannot be true.

In the end, I feel like this model is the most useful for normal brewing applications - if your yeast is four or more months old, you need to make a starter, regardless. Also, you may freely substitute your own viability percentages in this calculator if you so desire.


• All growth figures are based off of a 75% attenuation rate. Obviously, multiple factors can influence this, most notably the actual strain of the yeast used, but also the gravity of the starter wort, the temperature of the wort, and other factors. It stands to reason that attenuation rate will absolutely impact the final number of cells produced.


• I am assuming 2.72715 grams of extract per point of gravity per liter of starter.


• The calculator does not try to give precise starter volumes, as I feel that it would be rather difficult to work with recommended volumes like "1.15 liters" or "3.27 liters". Instead, it makes calculations based off of 500ml increments. If it cannot hit your target cell count at, say, 2 liters, the next try will be at 2.5 liters, and so on, until either your target cell count or your flask size is reached. If the calculator determines that you cannot build a large enough starter in a given step to reach your target cell count, it automatically calculates the next step up.

Note that you can customize any step of the process at any time, so if you want that 3.27 liter step, have at it!


• All growth rate data comes from the work done by Kai Troester of Braukaiser fame. My original intent was to include both the Braukaiser and Mr. Malty calculations, and allow users to pick from both. However, the more I delved into the subject, the more convinced I became that the Troester figures were more reliable. Troester makes his formulae freely available, while the Mr. Malty formulae are treated like something of a trade secret. Troester has published data from multiple experiments that seems to indicate repeatable results to back up his assertions, whereas I can't really find any experiments to back up (or back into) the Mr. Malty figures.

Specifically, the growth equations used in this calculator are, as follows:
◦For stirred starters, if the initial cell count is less than 1.4 billion per gram of extract, the growth rate is 1.4 billion cells per gram of extract.
If the initial cell count is between 1.4 billion and 3.5 billion per gram of extract, the growth rate is 2.33 - (.67 * initial cells) billion cells per gram of extract.
If the initial cell count is greater than 3.5 billion per gram of extract, there is no growth.
◦For simple (non agitated starters), the growth rate is .4 billion cells per gram of extract, up to an inoculation rate of 3.5 billion cells per gram of extract. If you exceed this, there is no growth.
◦For shaken starters, the growth rate is .62 billion cells per gram of extract, up to an inoculation rate of 3.5 billion cells per gram of extract. If you exceed this, there is no growth.
The formulae for stirred and simple starters comes from this article detailing estimating yeast growth rates, and the formula for shaken starters comes from this 2013 NHC presentation.


• Finally, realize that due to all of the assumptions above in regards to yeast viability and growth rates, no calculator will be able to accurately predict how many cells you have or will grow. According to the Troester models, you should assume a variance of +/- 15% in all such calculations. That being said, this yeast calculator will absolutely get you into the ballpark, and will help you to make noticeably better beer.

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