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Open Wooden Fermenter Opinions


phillyaaron

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We're pretty set on getting some open-top wooden tanks for our whiskey beer fermentations. We're considering getting drop-in glycol chillers for fermentation temp control and we'll recirc' with a centrifugal pump from the bottom port to a pipe we'll hang over the top edge. We'll probably clean with hot water, then steam-wand, in between fermentations. I was wondering who out there in ADI-land has any experience with these. Any secrets or pitfalls that we might not be considering? Does any body use them tilted or did you find someway to get a sloped bottom? Any breaking in tricks? Thanks!

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... we'll recirc' with a centrifugal pump from the bottom port to a pipe we'll hang over the top edge.

Maybe I have not understood this statement. Are you going to pump the fermenting beer out of the bottom of the fermenter and back in the top?

I asked a similar question on this forum about a year ago. I wanted to pump the fermenting beer through a heat exchanger to cool it.

I was told and have since confirmed it myself that you cannot pump fermenting beer with a centrifugal pump. It pumps for a couple of seconds then the lower pressure at the impellers creates foam as the CO2 gasses off.

I suspect you might get away with pumping if you used a very slow revving positive displacement pump (eg piston) that was mounted well below the outlet of the fermenter to maintain a positive pressure.

Also, if you do manage to pump it, keep the return line below the surface of the fermenter. Aeration during fermentation breeds more yeast and less alcohol.

I have a drop in refrigerated chiller that has a small impeller built into it for circulating the beer (originally for milk) although it is probably un-necessary unless you need very rapid cooling.

Steam wand. Does it have enough capacity to heat well into the wood? To kill bugs you need heat PLUS time. Wood is a good thermal insulator so a small wand may take a long time to heat into where the bugs are hiding. You don't want to kill every last one as that is the main reason for using wood, but you want to get rid of most of them.

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PeteB - Thanks for those tips. I'll be recirculating the beer post fermentation to (semi-)homogenize the grains and liquid before transferring to the still. I hadn't considered the dissolved CO2 problem, so we'll probably have to go with a positive displacement pump.

As far as the steam wand, we have no idea yet. That was the purpose of posting this thread; to get some feedback from other distillers about the nitty-gritty of open wood fermenters. Another thread http://adiforums.com/index.php?showtopic=5290 suggested a steam wand for sanitizing, so that's the plan we're going with right now.

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I have used a submersible centrifugal pump (dirty water type with open impellers) and it works well for stirring the mash. I have used it post fermentation to pump the beer to the still so CO2 doesn't seem to be a problem at this stage.

Cheap ones are under $100 if you want to try one out. Can't guarantee they will last but if it works then buy a better one when it dies.

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We are planning on going with open top wood fermenters. We don't have them yet but our tentative plan is to get custom tops (not air tight) to keep dust out but lt them breathe and we are going with stainless cooling coils to manage fermentation temps and crash cool out of the mash tun. We are purchasing a drum mixer and will either clamp it on build an holder so it can go straight down for mixing. A drum mixer may be easier than recirculating. In any event, when we're set up in a few months, I can let you know how its working.

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We use the open top fermentation and run the bug that make it through the nets with the rest of the mash as well. if I could do it over again...I would have bouth a stainless tank and had it "skinned" in cypress. Less work to take care of the wood and keep the staves from separating due to lack of using all 3 of ours at the same time.

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:) so, not a concern for contamination?

Hey, flavor's flavor, right?

But no, it's not really a concern. Any pathogens that make it from the fermenter into the kettle are going to be subjected to morbid levels of heat, then subsequently further destroyed in a high proof alcohol solution.

As to residual bacterial contamination of the fermentation vessel itself, there are two ways you can approach the issue. One is to hit the wood with a lightweight steam cleaner after every cycle (which is also good for the wood, keeps it nice and tight) or you can just rinse it out with a heads solution (which will enhance the next fermentation).

Old school. It's what we're all about.

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Yeah, I have a winery inhouse as well, so the fruit flies are part annoyance, and part a concern with the wine. I keep cheesecloth over the fermenter openings when in use, but that doesn't really keep the flies down, just out. I just hate it when a visitor is in the distillery talking with me, and shooing away fruit flies. I keep things pretty clean, don't get me wrong, but there's always something for them to eat.

Hey, flavor's flavor, right?

But no, it's not really a concern. Any pathogens that make it from the fermenter into the kettle are going to be subjected to morbid levels of heat, then subsequently further destroyed in a high proof alcohol solution.

As to residual bacterial contamination of the fermentation vessel itself, there are two ways you can approach the issue. One is to hit the wood with a lightweight steam cleaner after every cycle (which is also good for the wood, keeps it nice and tight) or you can just rinse it out with a heads solution (which will enhance the next fermentation).

Old school. It's what we're all about.

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I can understand the open fermenters, but I still don't understand why to use a material like wood, negatives seem to outweigh positives unless you are weighing tradition significantly (I can appreciate that).

Tradition is a big part of it.

The alternative, if you're going open to keep the cost down (among other things) is plastic.

Plastic scares me. On any level. Plastic is Bad.

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Impeller pump is your beast. Spin-fermenting will speed up your drop, too, and you can run higher starting gravs. A used wine pump is economical to buy and will last a long time. New impellers are cheap, and you can run plain old neoprene or Buna-N if your temps stay normal. The thing with open fermentation is to have it in a closed room, or one with limited cross flow of air...yeast will only make alcohol in an anaerobic situation, so you want to maintain your CO2 blanket. Make sure your pump return goes into the side of the vessel or the hose is submerged, or you will entrain a lot of air and possibly make something less tasty than you planned!

Out of curiosity, what exactly scares you about plastic?

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Apologies, not following but interested, are you talking about running the agitator/recirculator continuously? On an open top fermenter? Wouldn't the gas exchange at the surface create an environment ideal for yeast propagation, but not making beer? Sounds like this is a trade off between speed and efficiency. Sure it would ferment quicker, but you'd also lose quite a bit of sugar to additional yeast growth, no?

Seems to me that unless you were able to eliminate gas exchange at the surface, this isn't much different than running a starter on a stir plate. Even with a tiny amount of surface area, a deep head space, and simple cover, the gas exchange is still high enough to favor yeast growth over fermentation.

Or is this just something that you run occasionally, on a timer?

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I can understand the open fermenters, but I still don't understand why to use a material like wood, negatives seem to outweigh positives unless you are weighing tradition significantly (I can appreciate that).

The other two advantages that I hope to get from them (not actually using wood yet) are using less chemicals to clean, and, even with steaming, encouraging a local and unique microbiome. The latter is maybe a whole other thread for discussion though.

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........... encouraging a local and unique microbiome. The latter is maybe a whole other thread for discussion though.

This is the thread for it.

I think the reason most fermentation is done in a wooden vat is because of its unique microbiome. Over a period of time the wood will develop its own resident population of yeast and bacteria etc that will innoculate the wort and grow along with the innoculated yeast. That fermenter will have its own unique taste, isn't that a big part of what craft is about?

Otherwise in almost every other respect they are a pain. Harder to sterilise completely if you get the wrong bugs, and they can develop leaks if not kept wet, hoops can rust.

also I guess for a tourist facility they do look better than stainless or plastic.

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Out of curiosity, what exactly scares you about plastic?

I am also interested--- in scientific facts

HDPE at low temperature and low ABV where is the problem other than "in the mind"?

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  • 2 weeks later...

I am also interested--- in scientific facts

HDPE at low temperature and low ABV where is the problem other than "in the mind"?

If you're focused on scientific fact, you won't get any from me (in this case, anyway).

Yeah, I'm usually one of the first guys to trot out studies and equations to support any argument but in this case it's just my gut. My gut tells me that there are too many polymers in our lives and I don't feel compelled to contribute to that.

Historically, distillers have fermented in wood. The advent of shiny, expensive stainless steel is a relatively recent thing. Regardless of the merits of science, one of the reasons I'm in this game is to support traditionalism. So, I'm Good With Wood. :)

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I have to say that I have used HDPE with no issues several times.

But see, that statement doesn't really have any bearing on the concept of "too much isn't good", does it?

Have you ever hosed some spilled gasoline down a storm drain? Did you have any issues?

Ever flush household chemicals down the toilet? Any issues with that?

Lawn chemicals? Fertilizers? Pesticides?

Did any of those things result in "Instantaneous Three-Headed Syndrome"?

No, of course not. Because you, all by yourself, doing those things, don't have any particular impact on the overall picture save some minuscule, immeasurable contribution.

But here along the Jersey Shore we can be pretty sensitive to how tiny little things impact our lives and the greater ecosystem. The current plight of the coastal estuaries serves as a living (or not) reminder of that, every day.

So to me, such is the tale of plastics. Yeah, I know that drinking something that's spent part of its life in an HDPE barrel is, in itself, undoubtedly innocuous. But I'm also pretty certain that our constant exposure to long-chain polymers on a massive scale isn't beneficial in the long run. So I make the simple choice to avoid using them, wherever possible.

It's not fodder for debate. It's simply a personal choice.

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I guess that my thinking on this is that polymers derived from ethylene are generally inert in the conditions we subject them to. As long as you aren't throwing large amounts of acetone in the barrel or using it to ferment 14% strong mashes at 80 degrees on a constant basis, you should be fine.

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  • 11 months later...

We have some periods of time where we don't have a ferment in the Cypress Tanks. We typically try to keep them full of water so they stay sealed but that leads to mold which we need to rinse off and clean well before using. Any thoughts on something safe we could add to the water to keep them mold free?

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