I wanted to look at unitanks pros and cons today, as I’ve come to realize they aren’t universally understood.
When I’m working as a consultant; speaking to people about their upcoming projects, I’ve had to explain what unitanks plus how they work.
Then there’s they fact, people might call unitanks by different names depending on where they’re from. I was working with person from the UK (where I’m originally from) and he called them DPV’s (dual purpose vessels).
I’d never heard the term before, even though we’re from the same country!
When ordering equipment, the main debate regarding cellaring is; what types and how many vessels to get for your brewery. The three main tank types are:
Fermentation Vessel (FV)
An FV is where the sugar (wort) you’ve made, is fermented into alcohol, with some residual sugars usually left over. Furthermore, CO2 is produced as a byproduct of fermentation.
In traditional German lager brewing, after primary fermentation and cooling 32 – 39.2°F (0 – 4°C) the beer is moved to a separate vessel to mature.
The maturation time (traditionally 28 days) allows for the haze-inducing proteins and polyphenols to coagulate and fall the bottom of the tank. Furthermore, over time the beer mellows, becoming more delicate in taste.
Brite Beer Tank (BBT)
Once the beers matured, brewers may opt to clear the beer, by fining, filtering or centrifuging and sending to a BBT, from where it’s packaged.
Unitanks Pros and Cons – What is a Unitank?
Unitanks, will have carbonation stone just above the cone, that’s used to gas up the beer ready for packaging. So, beer can be fermented, matured, cleaned up, optionally dry-hopped and carbonated all in one tank.
The question when opening a brewery when discussing cellar tank configuration is:
Do I need fermenters, maturation vessels and brite tanks too?
The answer to this question isn’t a simple one, unfortunately. But I’ll try and break it down into bit-size chunks, to make it easier to digest.
What Type of Beer Are You Making?
If you’re mostly making lagers, it’s good to have all three cellar tank types. You’ve the fermenter for primary fermentation which is cylindrical-conical, like the one pictured above
The maturation tanks used in traditional lager brewing, are horizontal. These types of tank are coming back into fashion, as lager becomes more popular with craft beer drinkers
After spending around 28 days in the maturation tanks, the lager is then cleared ready for packaging. The beer usually clarified via filtering or centrifuging, then sent to the brite tank, ready for packaging.
Unitanks Pros and Cons – The Importance of Horizontal Tanks
The reason these tanks are preferred for lager maturation is:
a. Moving beer from upright fermentation vessel (FV) to a horizontal maturation tank reduces the hydrostatic pressure exerted on the yeast.
Meaning there is less stress on it. During the maturation phase (also known as cold stabilisation), things happen more slowly as the yeast comes to the end of its cycle.
As the yeast is less stressed, its happier carrying out its work, leading to a more refined beer.
b. The tanks are comparatively flat bottomed compared to an FV. Thus, providing a larger surface area of contact between the settled yeast and maturing beer. This allows more yeast to work on the beer to clean it up, pulling all the flavours together.
c. With a horizontal tank, essentially, you’re turning the beer on its side, the distance for the yeast, proteins and other solids to drop out of suspension is shorter.
Making Beer Easier to Clear
This makes it easier for the beer to clear. If left long enough, the beer can become crystal clear by itself. Although most modern breweries don’t have time or tank capacity to wait for beer to naturally clear.
So, horizontal tanks are key for traditional lager brewing. Allowing more yeast to work on the beer to clean up the “green” flavours thus bringing everything together. Becoming a clean crisp and refreshing brew.
Most modern breweries, if making significant amounts of lager will opt to have some maturation vessels.
What’s the Purpose of a Brite Beer Tank (BBT)?
If you don’t have several months to allow the beer to clean itself up, then, you need to clear it another way. The three main options are:
This is where you use a finings agent (SB3, Starbrite or something similar) to help clear the beer. For more information you can click here.
Two common options when using finings are; are to add finings in the unitanks and then pump around, to mix it thoroughly with the beer. You then wait for the yeast and sediment to settle (evacuating regularly) until the beer is clear.
When the beer is clear you can package it direct from the unitank. However, if it’s not clear enough, you can send it to a BBT, which helps clear the beer further.
The other option is to fine the beer, while it’s transferred to the BBT. Then wait for the beer to clear in tank, whilst you evacuate regularly before packaging.
You can use a filter to clear the beer. There are several options including lenticular and DE filtering. When you filter the beer, you transfer it out of the unitank via the filter (which clears the beer) sending the now clear beer to the BBT.
The centrifuge is similar to a filter. It’s used to clear the beer coming out of the unitank. Which goes via the centrifuge to clear it; then on to the BBT. So, the beer can be packaged. To learn more about centrifuging beer, please click here.
The Brite Beer Tank
So, the brite beer tank is for holding beer, after it’s been cleared. This is where the beer will be packaged from, once you’ve the correct CO2 content.
To learn more about beer styles and their recommended CO2 content read an article I posted on LinkedIn and get my FREE handy guide.
Beer doesn’t stay too long in the BBT, it’s best to package as soon as the beer is ready. I like to empty my BBT in less than 48 hours after filling if possible.
If you’ve filtered or centrifuged the beer, it’s possible to re-fill the BBT tank with another beer after it’s empty. As the beer you put inside previously was “clean”.
So, the next question is…
Can you just have unitanks? Using them as an emergency BBT if needed.
Unitanks Pros and Cons – A Closer Look
With its carbonation stone just above the top of the cone. In theory, you can use a unitank for all stages of the brewing process from fermentation to packaging.
However, let’s look at the cons just having a unitank:
If you want clear beer, then carbonating using the stone can be an issue. When you carbonate using the stone; it’ll kick up some of the yeast and hops (if you’ve dry-hopped). So, the beer isn’t clear.
Furthermore, if you’ve a racking arm on the tank, you’ll waste some beer (to clear the arm) or send some cloudy beer to be packaged.
Also, as it’s the same tank you fermented in. There’s sediment, protein and hard yeast stuck to the side of the vessel can break off ending up in the packaged beer.
As the carbonation stone is above the top of the cone, there’s a minimum amount of beer needed in the tank, to be able to carb it. For instance, if your send some beer back into unitank from a barrel, to add CO2, the beer level might be below the carbonation stone.
What are some other issues?
1. The cost of a unitank is more than for a brite beer tank of the same volume. Furthermore, a unitank will take up more space. Brite tanks are dish bottomed often with a 5° angle so, take up less space per volume compared to a unitank.
2. People, talk about the flexibility of having unitanks over a brite beer tank. However, if you’re consistently transferring beer off yeast and hops or filtering/centrifuging to another unitank, it’s basically a brite tank anyway. So, why not just have a BBT
Advantages of a Having a BBT
Let’s take a look at some of the advantages of having a BBT:
You Know Your Volume
When you send clear beer to the BBT yields are typically 100%. Now, if you’ve fined the beer on the way to the BBT; you’ll lose some beer when you evacuate, when clearing the beer. However, when it clears you know volume you can package.
When you package from a unitank, some portion of the beer is typically left behind. Furthermore, the sediment levels vary so, you can’t be 100% certain how much beer you’re able to package from the tank.
As I mentioned above, you can reuse a BBT more than once. Often breweries will re-fill a BBT, ten times before breaking it down to clean.
Brite tanks don’t need cleaning after every use because, unlike unitanks they don’t have the krausen line produced during fermentation. This saves time, chemicals and CO2.
Free Up Space
When you move a beer from a unitank, it becomes free to brew into again. You don’t have to wait for the beer to clear or for correct carbonation as that takes place in the BBT.
Unitanks Pros and Cons – Bringing it all Together
So, what are our takeaways?
1. If you produce lager; it makes sense to have all three cellaring tank types, fermentation vessel, maturation vessel and brite beer tank. It’ll lead to cleaner smoother beer.
2. If you’re mostly making ales, you don’t need maturation vessels. You can do most of the stages of beer making in the unitank including carbonating to the correct level.
3. Having a BBT, allows you to more easily clear beer, either by fining, filtration or using a centrifuge. It opens up your unitank to brew again. Also, you know how much beer you can package too.
4. Knowing how much beer you’ve in tank to package, can help when figuring taxes.
Unitanks Pros and Cons – Conclusions
When it comes to types and how many vessels you need for your brewery, it depends on individual needs. If you make a lot of lager, then having all three types of tank is advised.
At my first brewery, we made only lager. If I remember correctly (23-years ago!) we had:
- A 16-barrel (Bbl.) brewhouse
- 4 x 16 Bbl. (64Bbl.) FV’s
- Capacity for 160 Bbl. of lager in maturation tanks
- 1 x 16 Bbl. BBT
This set up allowed is to have a constant flow of beer for all our customers.
If you mostly make ales, then maturation tanks aren’t needed. You can do most stages in unitank.
If your making wheat beer or hazy IPA, which unclear as part of style, then packaging direct from the tank after correct carbonation is fine.
One caveat is, some bigger craft breweries and macros, will look for consistent haze and might process the beer another tank. To make sure the haze is consistent between batches.
However, if you making beer that’s still ale but needs to be clear. Say a West Coast IPA, where clearing the beer is true to style. You might want to clear and transfer to a BBT before packaging.
Unitanks Pros and Cons – Final Thoughts
Every brewer has their own take on this. However, my preference is, to have at least one BBT in your brewery irrespective of beer styles you make. The reason being:
1. You might have a stubborn beer that’s not clearing; having the ability to clear and send to BBT can save it.
2. If you’re adding adjuncts to beer, I like to transfer to BBT before packaging. It ensures the beer has a proper homogenous mix (flat bottom dish). Also, it’s easier to double check CO2 and gas if needed.
3. You now exact volume of beer you’ve available to package.
4. If you’re in a rush and need a tank to brew to. Sending a beer to BBT frees up a unitank for the brew. Also, if you’re short of beer, you can quickly clear a beer to have it ready in time (not ideal).
In most breweries, it’s recommended to have one BBT for every 4 to 5 FV’s you have. That’s my personal favorite set-up. With all the FV’s having the ability to spund the beer to naturally carbonate the beer.
To learn more about spunding beer to naturally carbonate it, please read my article on this site by clicking here.
If you opt to use unitanks where you can ferment, carbonate and package from then potentially you don’t need a BBT.
In a push you can transfer from one unitank to another to act as an emergency BBT. However, I’d still recommend having one BBT as it gives you some wiggle room in unforeseen circumstances like saving a beer that won’t clear or speeding up the beer cleaning process.
All breweries have unexpected situations even with best plans and brewing practices. Having that one BBT among many unitanks could be a lifesaver.
This is my personal opinion, from my years of experience. Others may disagree. If you’ve another view point, I’d love to hear it.
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My name is Neil and I’m a brewing consultant. I help people on their brewing projects; either setting up a new brewery or expanding operations.
I’ve several installations under my belt with the last being a 20HL production brewery at the end of 2020. Please see pic below of the installation.
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