In addition to speed, temperature and level of oxygen, choosing a fermentation vessel is one of the most vital decisions a winemaker can make in the fermentation process that will affect the finished wine. 

#1: Easy Access for Punch Down (for Reds)

Why: Punch down process is a key step to a good ferment for red wine. This means being able to easily access the must is of the utmost importance in a good fermentation vessel.

Strong Choices: Stainless Steel, Poly Tanks, Poly Bins

Stainless Steel Tanks; Poly Tanks like Flextank Stackers, Egg Tanks, Dexter Tanks; plus Versa Bins used for open-fermenting all have wide openings which lend perfect access for Punch Down.

Weak Choices: Barrels

While barrels work for aging and storing wine, and can be used to ferment white wines, they simply don’t allow access for the key punch down process necessary in fermenting reds.

#2: Absence of Unwanted Chemical Reactions

Why: Certain vessel materials can react poorly with the acid in the wine and add unwanted flavor to the finished product.

Strong Choices: Stainless Steel, Poly Tanks, Poly Bins

Both stainless steel tanks and poly vessels have been scientifically proven to allow the natural chemical reactions of fermentation while not imparting any unwanted chemical reactions or taste into wine.

Weak Choices: Concrete

In concrete tanks, metallic compounds can form during the fermentation process due to the acid reacting with the concrete. This can give your wine a metallic taste.

#3: Maneuverability

Why: Moving your vessel is an important factor to consider when choosing a tank. Often as cellars operate and grow, moving and transporting vessels to different spaces is a regular part of that process.

Strong Choices: Poly Tanks, Poly Bins

Poly tanks and bins, though extremely durable, are also very lightweight and maneuverable. This makes transporting empty or full to different locations within the cellar, such as cleaning stations, a breeze.

Weak Choices: Stainless Steel, Concrete

Most stainless steel tanks and concrete tanks are very heavy and difficult to move. Maneuvering these tanks comes with a higher risk of damage or cracks to the tank.

#4: Easy Sanitation

Why: Microbial Bacteria can cause mold growth.

Strong Choices: Stainless Steel, Poly Tanks

The smooth walls of a stainless steel or poly tank make sanitation both very low cost and easy to do.

Weak Choices: Concrete, Barrels

Concrete and Barrels both have very porous surfaces that can harbor harmful microbial bacteria. For both of the vessels, maintaining proper sanitation can be expensive and a hassle.

#5: Multipurpose/Versatility

Why: When looking to add fermentation vessels to your operations, it can be a wise economic decision to consider the versatility of the vessel and ask yourself is fermentation the only function that the vessel performs for me?

Strong Choice: Poly Tanks

With the proper OTR choice and temperature accessories like Fermentation Locks and Thermometers, poly tanks like Flextanks can be a flexible tank for use in fermentation, maturation, transportation, and storage.

Medium Choice: Stainless Steel

Stainless steel tanks are a popular choice for fermenting. For some smaller wineries, however this is the only function they are used to perform which makes them an expensive cellar addition.

Weak Choice: Oak Barrels

Oak Barrels are a popular choice for aging, but are not able to perform fermenting functions for reds like punch down without serious and costly modifications that render them unusable for maturation.

#6: Cost

Why: Cost is one of the biggest decisions that can make all the difference in keeping a smaller professional winery running in harder economic times as market competition grows.

Strong Choices: Poly Tanks

Gallon for gallon, Poly Tanks are the undisputed winner of this category by a substantial margin reigning as the most affordable vessel for fermenting wine.

Weak Choices: Stainless Steel, Concrete, Oak Barrels

These options can cost more than eight times as much as Poly Tanks for performing the same, or fewer, tasks.

https://flextank.com/2023/10/25/6-features-to-look-for-in-an-excellent-fermentation-vessel/