conical vs flat bottom fermenters

[HDNB]

i don't have enough fermenters. so i have got over zealous a few times and just fermented in my still, but with consistently bad results

if i do the exact same thing and put it in my conical fermenter they go off without a hitch.

the only difference of note is the still is SS and flat bottomed. the fermenter is a conical bottom HDPE tank.

it not that they don't finish (well ok, a couple didn't finish) but they are sllloooowwww in the still.

up until today i thought there was other factors for stalls or slowness, but i waS pretty careful with this last one, had a 10% potential, all malt rye used some lab enzymes to make sure i got all there was to offer and i also went a bit hot for all malt at 160* in hopes of pasteurization but used GL and sebflo in ph and temp ranges to ensure saccharification...cold crashed to 105* proofed the yeast, hit it with a big colony at 105* and the ferment started up like fireworks and went strong for 5 days. today it's still working, but slow and sg is still at 1.04.
smells ok, looks a bit slimier than usual taste is tart but has sweetness still.

anybody notice a difference in flat bottom vs conical?

[shadylane]

I've had better luck with flat bottom fermenters, than conicals
The flat bottom did have a heated water jacket.

Maybe the mash protocol wasn't right
Did you use any HTL with the GL and sebflo

[HDNB]

sure did.

i duplicated the mash in time, temp and additives in the conical...behaves totally differently.

[shadylane]

sure did.
I duplicated the mash in time, temp and additives in the conical...behaves totally differently.

You mashed and fermented in a flat bottomed boiler
For the conical, you mashed in the boiler then fermented in the conical

[Single Malt Yinzer]

Always been curious about this. Subbed in. Only thing I know is that with a conical you get less lees exposure, but I didn't think it would have as big an effect as you describe.

Fermenters same size/height/width/depth?
Open or closed?

Maybe the HDPE is cooling more/less than the SS?

[Saltbush Bill]

the only difference of note is the still is SS and flat bottomed. the fermenter is a conical bottom HDPE tank.

Maybe the HDPE is cooling more/less than the SS?

I'm also thinking along the lines that its not the shape but the material the fermenter is made of.
Could it be that the HDPE fermenter is better at holding the heat produced by the yeast as it works and the stainless is conducting heat better to the surrounding atmosphere hence the mash/ wash is cooler.
A warmer ferment is causing a faster and more vigorous ferment?

[fizzix]

Found THIS chart and stainless indeed conducts heat better than HDPE.

[Bushman]

I love it when members think out loud. I think you guys are on to something!

[hellbilly007]

I've been looking at conical inductor tanks here lately. I'm interested in any pros and cons. Sub'd to see where this goes.

[HDNB]

sure did.
I duplicated the mash in time, temp and additives in the conical...behaves totally differently.

You mashed and fermented in a flat bottomed boiler
For the conical, you mashed in the boiler then fermented in the conical

zees iss correct. mashed in a flat bottom SS mash tun, mixing, heating, cooling... all that good stuff. then transferred to the still (flat bottom SS) and to the conical HDPE at the same temperature (100*) they both are at 80* currently (at the top)
strange enough the grain trub is warmer at the bottom on both (about 82*)
using red star.

noted: the heat transfer....i understand what you are saying but the temperature of both has cooled at basically the same rate to the same room temperature. well , really a bit above the room temp as i use a radiant infra red heater that directly heats them both (SS still is closer to the "hot" end of the heater) and of course, there is the heat from the yeast activity.

[Single Malt Yinzer]

It's some factor that is limiting growth/speed/attenuation of the yeast. If you look at the metabolic pathways for yeast there's something that is being limited in one and not (as much) in the other. https://www.khanacademy.org/science/bio ... espiration" onclick="window.open(this.href);return false;" rel="nofollow

I don't believe this is a factor but posting this anyhow: Could it be that the HDPE is getting more oxygen for growth? https://www.homebrewtalk.com/forum/thre ... ic.298055/" onclick="window.open(this.href);return false;" rel="nofollow

Another idea (maybe a little more likely): Is the conical shape causing better convection circulation? That would make it easier for the yeast to come into contact with sugars speeding fermentation. Is the HDPE fermenter deeper when filled with wash? Due to the cone it might be doing this. Deeper = more convection movement.

[shadylane]

Maybe the conical fermenter is better at keeping the yeast in suspension.
On the flat bottom, yeast is settling on the bottom were life is more difficult amongst the trub.

[HDNB]

that's kinda what i've been eyeing up.

when i did my last rum, CO2 bubbles rose vigorously from the centre of the conical, nosomuch on the outer "ring" i can imagine this produces a better circulation. I fermented rum in my mash tun that time and the bubbles were even throughout the surface...and it too took longer.

of course with a grain cap i cannot see how the bubble pattern differs from vessel to vessel. i do know that the grain cap stays up much longer on flat bottoms than it does on conical.

[shadylane]

I wonder what happens with an agitator
conical vs flat bottom fermenters

[LWTCS]

I get lots of requests for a pill shape ( dome bottom) rather than conical for the guys doing grain in fermenting and distilling.
But this is more for the sake of user friendliness.

The pill shape allows the agitator to more easily put the solids into uniform suspension prior to pumping over to the kettle.
Otherwise a "dryer" plop of the settled grains can jamb your pump.
The other consideration is if your fermentation vessel is twice the size of your kettle for example, you'd want to agitate prior to charging your kettle to insure that everything in the fermenter is uniformly installed into each kettle charge. Otherwise the distiller would likely have a first kettle charge with far more solids than the second. And that would potentially affect the run in several ways.

I haven't really heard of the shape otherwise affecting the quality or speed of the fermentation. There are a bunch of em out there using square totes.

[Anyhowe]

There should be no material difference in fermentation berween the two vessels. I suspect you have some other process variations at play.

[Single Malt Yinzer]

Shape does matter:

https://www.winesandvines.com/news/arti ... t-Appetite" onclick="window.open(this.href);return false;" rel="nofollow
https://www.decanter.com/learn/concrete ... er-316358/" onclick="window.open(this.href);return false;" rel="nofollow
https://www.forbes.com/sites/thomaspell ... 2af53d3182" onclick="window.open(this.href);return false;" rel="nofollow

[LWTCS]

Interesting how all three articles only reference the wine side.

[Anyhowe]

Interesting how all three articles only reference the wine side.

Yes it can matter but not to the extent he is experiencing.

[LWTCS]

No reference to actual data beyond anecdotal.

The owners of Boundry Oak have opened their distillery in a building that was formerly a plant that manufactured large concrete drainage structures, catch basins, etc.

Evidendently they've repurposed a few of the concrete tanks for fermentation. They seem to be very happy with what they are doing. But I would reckon those tanks are square.

[HDNB]

ya, my evidence is all anecdotal too. i only occasionally get around to having everything empty where i think i should start one in the still to reduce pumping to once, instead of twice.

maybe the next time i can split the mash and do 1/2 in the still and 1/2 in the fermenter and eliminate a few more possibilities.

short of taking sample to have lab tested, anyone have any other experiments come to mind?

[shadylane]

Put small electric space heater under the flat bottom fermenter.

[Stonecutter]

Maybe the conical fermenter is better at keeping the yeast in suspension.
On the flat bottom, yeast is settling on the bottom were life is more difficult amongst the trub.

Shady have you (or anyone else for that matter) used a conical with your sugar shine? I’m wondering if the shape may trap the oyster shells and inhibit their usefulness.

Edit: being there’s little to no “trub” in a sugar wash it’s probably not a big deal but if anyone can give their input it would be appreciated.
Cheers

[HDNB]

Maybe the conical fermenter is better at keeping the yeast in suspension.
On the flat bottom, yeast is settling on the bottom were life is more difficult amongst the trub.

Shady have you (or anyone else for that matter) used a conical with your sugar shine? I’m wondering if the shape may trap the oyster shells and inhibit their usefulness.

Edit: being there’s little to no “trub” in a sugar wash it’s probably not a big deal but if anyone can give their input it would be appreciated.
Cheers

you may have missed this above:

when i did my last rum, CO2 bubbles rose vigorously from the centre of the conical, nosomuch on the outer "ring" i can imagine this produces a better circulation. I fermented rum in my mash tun that time and the bubbles were even throughout the surface...and it too took longer.

this basically a sugar shine, so i think there would be no problem with shells working from the low point, there seems to be a lot of yeast action there.

Updates: this rum, which was awful when new and still crappy after two years in an ex bourbon barrel has come right around to a fruity monster after 5 years...
the ferments in the still were overheating. in the hdpe conicals, it had a more uniform heat dispersion. In the still i was getting a big temperature spike in the first 12 hours damaging the yeast.
hard to figure out because it was happening overnight on the first night and still fermenting after that but the yeast was damaged enough to slow it right down. i came up with a way to strip excess heat away the first night and problem resolved, after the first night no worry about cooling,it didn't produce enough heat to "overheat" after getting through the first 12 or so hours.
I'd assume that the extra heat would be during aerobic phase and when it goes anaerobic it doesn't produce as much heat.

[VLAGAVULVIN]

My conical one is OK for the yeast removal, imo. I prefer it for beer, especially for its light transparent kinds.

The same story with the fermented wort. The less I want to boil yeast during the stripping run, the more I think about the conicals.

[shadylane]

Maybe the conical fermenter is better at keeping the yeast in suspension.
On the flat bottom, yeast is settling on the bottom were life is more difficult amongst the trub.

Shady have you (or anyone else for that matter) used a conical with your sugar shine? I’m wondering if the shape may trap the oyster shells and inhibit their usefulness.

A while back I made and used a conical SS fermenter.
Can't say if the shape trapped the oyster shells and inhibited their usefulness.
Because the shell grit was in a sock hung in the middle of the fermenter.
I only used the fermenter a couple times before trading it to a beer brewer.
He was happier than a pig in shit with the trade.

The conical fermenter had a water sealed cap. A bottom drain and a side drain made so the the level could be adjusted. The brewer also got all the the electrics needed to keep the temp within a degree.
The fermenter even came with a stand that had wheels.

Any way back to the story.
I can see a need for a conical fermenter when brewing wine or beer.
Not so much for fermenting a sugar shine.
A flat-bottomed fermenter with the drain as low as possible on the side, works as good or better.
All that's needed is a way to gently tip the fermenter a little.
So the last of the clear wash can be drained off
The majority of the trub will lay on the flat bottom and not be disturbed.

Before I forget.
Heat a flat-bottomed fermenter from below.
Billions of yeast will thank you for it.

[Saltbush Bill]

after the first night no worry about cooling,it didn't produce enough heat to "overheat" after getting through the first 12 or so hours.

Bigger sized Rum washes can create a lot of heat in the first 12/18 hours ...they seem to settle down a bit after that .......Ive nearly "cooked " a couple myself when not paying attention.......Id imagine that its a lot cooler there so you do have that advantage at least.

He was happier than a pig in shit with the trade.

Sounds like the other fella involved in the trade wasn't to displeased either.

A flat-bottomed fermenter with the drain as low as possible on the side, works as good or better.
All that's needed is a way to gently tip the fermenter a little.
So the last of the clear wash can be drained off
The majority of the trub will lay on the flat bottom and not be disturbed.

Stonecutter what is described above is the exact method that I use with my 200L stainless flat bottom fermenter......my tap is about 1 inch from the bottom.......this method works perfectly for me. Just give your mash or wash a few days to settle properly before draining the fermenter.
Nother trick is to turn the tap on very quickly for a couple of seconds then turn off. Toss that bit , any yeasty shit sitting in the tap area can be got rid of that way first.
What is best for other reasons I cant comment , never have had one of them fancy conical bottom jobs.

[Stonecutter]

A while back I made and used a conical SS fermenter.
Can't say if the shape trapped the oyster shells and inhibited their usefulness.
Because the shell grit was in a sock hung in the middle of the fermenter.
I only used the fermenter a couple times before trading it to a beer brewer.
He was happier than a pig in shit with the trade.

The conical fermenter had a water sealed cap. A bottom drain and a side drain made so the the level could be adjusted. The brewer also got all the the electrics needed to keep the temp within a degree.
The fermenter even came with a stand that had wheels.

Any way back to the story.
I can see a need for a conical fermenter when brewing wine or beer.
Not so much for fermenting a sugar shine.
A flat-bottomed fermenter with the drain as low as possible on the side, works as good or better.
All that's needed is a way to gently tip the fermenter a little.
So the last of the clear wash can be drained off
The majority of the trub will lay on the flat bottom and not be disturbed.

Before I forget.
Heat a flat-bottomed fermenter from below.
Billions of yeast will thank you for it.

I’m sure he was.

What spurred you to get rid of the SS conical?
I’ve had my eyes on one for quite some time. I’m currently using plastic fermenters, the 6 gal. “Big Mouth Bubbler”, with a tap on the bottom. They work great but I’d like to move on to something bigger and more durable.

[dmw_chef]

Conicals are a complete waste of money for anyone on the homebrew scale. Full stop.

At least a dozen times I've fermented the exact same must, in almost identical volumes, side by side in both stainless bucket and a stainless conical and they had identical fermentation kinetics.

Conicals are easier to clean, especially if it is a size of fermenter that you can't easily lift. They are great for harvesting yeast.

Any differences in fermentation kinetics you see will only really apply to commercial scale brewing.

[Stonecutter]

Cleaning is a Royal PITA. Anything that helps with that is a plus.