Fermentation Open tank or Closed?

[Lorenzo]

Hi All,

Trying to decided what will work best for our new distillery, we haven’t purchased Fermenters yet , but some of the feed back we are getting is open. VS closed top, being new to distilling I thought I would ask the forum about this as it doesn’t seem to make much of  a difference, but there seems to be some discussion on Wild yeast, bugs and other things contaminating the ferment, from the companies trying to sell us the tanks,do a majority of you, (distillers) have closed tanks, we intend to produce Whiskey , Rum, and Brandy. I have seen lots of the open cypress tanks, both in the South and of course in Kentucky, and really would like the open type what’s the consensus?

Please comment, Thanks. Lorenzo

[Silk City Distillers]

For grain in whiskey, open top tanks will work fine, but if you use open top, you'll want to have some kind of lids.  Otherwise, you'll be swatting fruit flies for 9 months of the year.  These will work fine for rum as well.  But, shifting to rum, you want to consider what you'll be doing with yeast.  Conicals are ideal for harvesting/reusing yeast, and these will generally always come closed top.  However, conicals can sometimes be problematic for on-grain fermentations - grain can sometimes pack the cone, making pumping difficult, or can get left behind, which makes cleaning a problem.  No easy decision.  Harvesting/reusing yeast will likely pay back the cost differential of a conical vs open-top tank in a year.  $25-50 a ferment, one ferment a week, thats an easy $1,000-2,000 cost savings per year from re-pitching yeast.  

[Southernhighlander]

Open top fermenters are best for grain in mashes.  One of the benefits of open top fermentation is the fact that the heat escapes out of the top so you don't need as much cooling.  That being said it is best to make a lid from slats and a fine stainless mesh.  You just lay it on top of the fementer when it's in use and it will keep out insects and dust and debris while still allowing for the heat to escape.  In my opinion conical close top fermenters are best for off of the grain fermentations.  Conicals are not good for grain in because the grain can compact in the bottom.

[Lorenzo]

That was great information Silk & Paul, my lack of experience in sourcing the proper tanks is showing, wasn't sure that you could harvest and reuse the yeast form a Rum wash, thought that it was done once the ferment was over !! Like the implied savings , haven't checked out the conical fermenters price wise, thanks so much for pointing me in that direction.

[Silk City Distillers]

1kg of yeast pitched in a 2000l rum ferment yields nearly 20l of thick yeast - or in US terms - a 5 gallon pail full - 40  pounds worth.

[indyspirits]

1 hour ago, Silk City Distillers said:

1kg of yeast pitched in a 2000l rum ferment yields nearly 20l of thick yeast - or in US terms - a 5 gallon pail full - 40  pounds worth.

Do you actually harvest rum yeast? Any concern about what else may be growing? My boss is always riding my ass about lowering COGS and harvesting yeast would go a long ways toward that.  

[dhdunbar]

Okay, I'm not a distiller, but I recall some real C02 problems around large, open top fermenters for wine.  Perhaps the size mitigates.   I'll leave it as a question about whether someone should take care to vent properly.  I sure don't know.

[Silk City Distillers]

48 minutes ago, indyspirits said:

Do you actually harvest rum yeast?

Yes, but I only go 1 generation.  Haven’t tried acid washing yet, but if we really ramp rum production, I’d do this and pitch a few generations.

 

[Southernhighlander]

50 minutes ago, dhdunbar said:

Okay, I'm not a distiller, but I recall some real C02 problems around large, open top fermenters for wine.  Perhaps the size mitigates.   I'll leave it as a question about whether someone should take care to vent properly.  I sure don't know.

All fermentation areas should have proper venting when open top fermenters are used.  I also suggest C02 detectors.

[MGL]

I started off doing open top fermentation for whiskey and switched to closed years ago. I will never do open ever again because it's a complete pain.

I don't notice much difference in fermentation temp with open vs closed. I think the difference is marginal. With open you can't direct the co2 or the smells and you'll die of old age before you ever get the fruit flies under control.

I don't agree with southerns last statement of all fermentation areas should have proper venting with open top. The reason I disagree is that if the blowoff isn't vented outside that you'll have the exact same amount of co2 present in your facility if the tanks are open or closed. It's just tens of thousands of dollars cheaper to vent closed tanks outside the building than to turn over the air to create a safe workplace with open fermentation. If you are unfortunate enuf to be in the northern states you'll have to pay for all the heat you lose in the winter because you'll need to turn over the air in your distillery multiple times per day.

Just because some places do a dirty ferment and think it's cool to stick their hands in the mash doesn't mean it's right. You'll also make a more consistant and probably better product by having a closed and clean fermentation which will also help your sales in the long run.

but its yer business, if you want to stick various body parts into your mash then go right ahead. Disclose your practice on the label and I bet nobody will want to buy it!

[Silk City Distillers]

We had lids and agitators fabricated for our Custom Metalcraft open top tanks.  Every distiller that uses open top totes asks me how they can buy them.

 

[indyspirits]

4 minutes ago, Silk City Distillers said:

We had lids and agitators fabricated

Biggest regret on our semi-conicals (15 degree rather than 60 degree bottom) is that at the very least we didn't have flanges installed which could accommodate an agitator.  Im curious what your impeller arrangement is like on these. 

 

 

[Silk City Distillers]

The agitators are fairly simplistic low speed mixers.  They are 1/2hp geared to 40 or 50rpm, and use a directly coupled shaft.  I don't have the impeller measurements handy, but it's flat stock that was machine bent into a pitch blade design.

It only provides enough agitation to suspend grain solids that are on the bottom of the tank, rouse yeast off the tank bottom, or to be able to break up the cap during fermentation (automatic punch-down).

 

 

[Silk City Distillers]

Not to mention that mixers cut my crash cooling time in half.

[indyspirits]

1 hour ago, Silk City Distillers said:

Not to mention that mixers cut my crash cooling time in half.

I assume then that those CMC tanks have the jacket on one side? 

 

 

[Silk City Distillers]

Yep

[rickthenewb]

On 3/5/2018 at 3:19 PM, Southernhighlander said:

Open top fermenters are best for grain in mashes.  One of the benefits of open top fermentation is the fact that the heat escapes out of the top so you don't need as much cooling.  That being said it is best to make a lid from slats and a fine stainless mesh.  You just lay it on top of the fementer when it's in use and it will keep out insects and dust and debris while still allowing for the heat to escape.  In my opinion conical close top fermenters are best for off of the grain fermentations.  Conicals are not good for grain in because the grain can compact in the bottom.

Hi Paul, if you were doing a 200 gallon batch would you need cooling with an open top fermentation?

[Southernhighlander]

Rick,

 

Yes you may need a little cooling.  You could go with dimple jackets on 2 sides or if you want to save some money  we have removable stainless cooling coils for $350.00 each. 

[Southernhighlander]

If anyone has jacketed fermenters that they want to crash cool in, we have 1/2 hp geared 45 rpm agitators for $1,450.00 each.  this price includes the paddles  These are not needed for keeping your fermenter temps down, they are just to help speed up your crash cooling, if you are using your fermenters for that purpose.  We also have tube in tube heat exchangers and other crash cooling equipment in stock.