KegLand Kegmenter vs. Corny Keg: Fermenting in Steel

Choosing between a KegLand Kegmenter and a standard Corny Keg for stainless steel fermentation boils down to desired capacity, pressure management, and ease of cleaning. The Kegmenter offers superior volume, dedicated features like a thermowell and larger opening for dry hopping, and higher pressure ratings, making it ideal for advanced pressure fermentation. A Corny keg, while compact, is limited by smaller capacity and lower safe fermentation pressures.

The Brewer’s Hook: My Journey to Steel Fermentation

For years, I swore by glass carboys. They were cheap, readily available, and I could watch the fermentation magic unfold. But then came the breakages, the persistent battle with krausen clinging to constricted necks, and the general anxiety of cleaning. The moment I started experimenting with pressure fermentation, I knew glass wasn’t going to cut it. My initial foray into fermenting in steel was with standard Corny kegs. I’d seen others do it, and the appeal of a closed-loop, oxygen-free transfer was undeniable. I brewed a simple West Coast IPA, fermented it in a Corny, and for all its convenience, I found myself wrestling with a few critical limitations.

The biggest headache? Dry hopping. Trying to get a hop bag through a 2-inch Corny lid was a frustrating exercise in futility. Then there was the volume limitation and the constant worry about over-pressurizing. It worked, but it wasn’t elegant. That’s when I started looking for dedicated steel fermenters, and the KegLand Kegmenter entered my brewery. My experience shifted overnight, offering a level of control and ease I hadn’t thought possible. This article isn’t just a comparison; it’s a reflection of my practical journey, the data I’ve gathered, and the lessons learned in the pursuit of better beer.

The Math: Understanding Volume & Pressure Dynamics

When you’re fermenting in steel, especially under pressure, the math isn’t just academic; it’s fundamental to success. I’ve spent countless hours crunching numbers to optimize my systems, and here’s a look at the critical calculations.

Usable Fermentation Volume

This isn’t just the advertised volume. You need headspace for krausen and CO2 production. My rule of thumb is 10-15% headspace for most ales and 5-10% for lagers (due to less vigorous krausen).

Kegmenter (30L):

• Target headspace: 10%
• Usable Volume = 30L * (1 – 0.10) = 27 Liters

Corny Keg (19L):

• Target headspace: 10%
• Usable Volume = 19L * (1 – 0.10) = 17.1 Liters

This seemingly small difference significantly impacts batch size. If I’m aiming for a 20L batch to fill two Corny kegs, the Kegmenter is clearly the better choice for a single fermenter.

Pressure Fermentation Calculations (Spunding)

The goal of pressure fermentation is to spund – that is, to ferment under controlled pressure, using the CO2 produced by the yeast. This requires precise management.

Key Principle: Every 1 point drop in Specific Gravity (e.g., from 1.050 to 1.049) in 1 liter of wort produces approximately 0.5 grams of CO2. To convert CO2 mass to volume, I use the molar volume of a gas at STP (22.4 L/mol for CO2, molar mass ~44 g/mol), so 1g CO2 is roughly 0.51 L at STP.

Let’s say I’m fermenting a 20L batch from OG 1.050 to FG 1.010 (a drop of 40 points).

1. Total CO2 Produced: 20 L * 40 points * 0.5 g/point/L = 400 grams CO2.
2. Total CO2 Volume (at STP): 400 g * 0.51 L/g = 204 Liters CO2.

Now, how much pressure will that generate in my headspace? This is where equipment ratings are critical.

Corny Keg (19L): Rated for 130 PSI burst pressure, but safe fermentation pressures are typically 0.7-1.0 BAR (10-15 PSI). A standard 15 PSI PRV is common.

• If I set my spunding valve to 10 PSI (0.7 BAR), any excess CO2 above that pressure will be vented.
• This means the 204L of CO2 produced is mostly vented, with only a small fraction retained to maintain the desired pressure in the headspace (approx. 1.9L at 10% for a 19L keg).
• It’s crucial not to exceed the safety rating of the PRV, and even more crucial not to run a Corny keg at its burst pressure for fermentation. My experience suggests sticking to 10-15 PSI maximum.

Kegmenter (30L): Designed with a stronger dome, often rated up to 4 BAR (58 PSI) operating pressure, but usually fitted with a 2.5 BAR (36 PSI) PRV for safety.

• With a 2.5 BAR PRV, I can confidently ferment lagers at 1.0-1.5 BAR (15-22 PSI) or even some ales at 0.3-0.5 BAR (4-7 PSI).
• This higher pressure tolerance gives me much more flexibility for controlling ester production and increasing CO2 absorption during fermentation, leading to naturally carbonated beer faster.

This math confirms that for serious pressure fermentation, especially for larger batches or higher pressures, the Kegmenter offers a significant advantage in safety and control.

Step-by-Step Execution: Fermenting in Steel

My process for fermenting in steel has evolved over two decades. Here’s how I approach it, highlighting the nuances of each vessel.

1. Cleaning and Sanitization

1. Initial Rinse: Immediately after emptying, I rinse with hot water. For a Corny keg, I usually disassemble the posts, dip tube, and lid. For the Kegmenter, the large opening makes rinsing incredibly easy; I just blast it with the hose.
2. PBW Soak/Circulation:
   • Corny Keg: Fill with 1-2 gallons of warm (40-50°C) PBW solution (1 oz per gallon), seal, and shake vigorously. I then let it soak for at least 30 minutes, often overnight for stubborn krausen rings. I also run the solution through the dip tube and posts.
   • Kegmenter: With its wider opening, I can use a keg washer with a spray ball, or simply fill it with 10-15 Liters of warm PBW solution and scrub with a long-handled brush. The ability to visually inspect and manually scrub every surface is a massive win here.
3. Rinse: Thoroughly rinse with hot water until all PBW residue is gone.
4. Sanitization:
   • Corny Keg: Fill with 1-2 gallons of Star San solution (1 oz per 5 gallons), seal, shake, and let sit for 5-10 minutes. Depressurize through the PRV and let the foam drain.
   • Kegmenter: I use 5-10 Liters of Star San, then seal and rock it around to coat all surfaces. Alternatively, I’ll spray down the interior with a pump sprayer. For both, I ensure the lid, thermowell (Kegmenter), and all fittings are thoroughly sanitized.

2. Wort Transfer & Yeast Pitching

1. Cooling & Transfer: After chilling my wort to pitching temperature (e.g., 18°C for an ale, 10°C for a lager), I transfer it from my brew kettle directly into the sanitized fermenter. I use a sanitized silicone tube, ensuring minimal oxygen pickup.
2. Yeast Pitching:
   • Corny Keg: I pitch yeast through the small lid opening immediately after the transfer. It’s a bit fiddly, but manageable.
   • Kegmenter: The large 4-inch opening is a dream. I can easily pour in my yeast, attach the thermowell probe, and seal the lid.
3. Sealing: I ensure the lid is properly sealed, and all connections (gas/liquid posts, PRV, spunding valve) are tight.

3. Fermentation (Pressure Management)

1. Spunding Valve Setup:
   • Corny Keg: Attach a spunding valve to the gas post. I typically set it to 7-10 PSI (0.5-0.7 BAR) for ales, allowing for some natural carbonation and ester suppression without stressing the keg.
   • Kegmenter: I use a robust spunding valve, often setting it higher, e.g., 15-20 PSI (1.0-1.4 BAR) for lagers to achieve ultra-clean profiles, or 5-8 PSI (0.3-0.5 BAR) for ales. The Kegmenter’s higher pressure rating provides a safety buffer.
2. Monitoring: I closely monitor fermentation activity via my spunding valve’s gauge and specific gravity readings. The thermowell on the Kegmenter is invaluable for accurate temperature control with an external controller. For a Corny, I rely on stick-on thermometers or probe taped to the side, which is less precise.

4. Dry Hopping

1. Corny Keg: This is a challenge. I’ve resorted to using hop socks crammed through the small opening, which restricts hop movement and contact. For pellets, I’ve had success using a sanitized pipe or funnel to drop them directly in, but it’s messy and increases oxygen exposure.
2. Kegmenter: This is where the Kegmenter truly shines. Its large opening allows me to easily add hop pellets directly, or use a large hop bag for easier removal. I often do this under pressure (a “soft crash” to 1-2°C, then vent residual pressure, add hops, seal, and bring back up to fermentation temp for 24-48 hours, then cold crash again), reducing oxygen ingress significantly.

5. Cold Crashing & Transfer to Serving Keg

1. Cold Crashing: Once fermentation is complete and gravity is stable (e.g., **1.010 for an ale, 1.008 for a lager**), I cold crash both vessels to **0-2°C (32-36°F)**. I usually maintain the fermentation pressure during this phase to aid in CO2 absorption.
2. Transfer: This is the beauty of closed-system steel fermentation. I connect the gas post of the fermenter (with 1-2 PSI positive pressure) to the gas post of a sanitized serving keg. The liquid post of the fermenter connects to the liquid post of the serving keg. I open the PRV on the serving keg just enough to create a slow flow, transferring the beer entirely oxygen-free, directly under pressure. The Kegmenter’s floating dip tube ensures I’m always drawing clean beer from the top. With a Corny, I have to be mindful of yeast cake at the bottom.

This systematic approach, refined over two decades, ensures consistent, high-quality beer with minimal risk of oxidation. For more detailed guides on optimizing your transfers, visit BrewMyBeer.online.

Troubleshooting: What Can Go Wrong

Even with meticulous planning, brewing is an art with variables. Here are common issues I’ve encountered with steel fermenters and how I tackle them.

• Stuck PRV/Over-pressurization: This is a serious safety concern. I’ve had PRVs stick due to krausen or dried wort. Always use a blow-off tube for the first 24-48 hours of vigorous fermentation, even with a spunding valve, as a backup. Regularly test your PRV by pulling the ring. If pressure builds unexpectedly and doesn’t vent, carefully open the gas post or PRV.
• Leaks: Small leaks around the lid or posts can lead to oxygen ingress and pressure loss. I always spray connections with Star San solution after sealing; any bubbles indicate a leak. Lube your O-rings! My mistake early on was not lubing the Corny keg lid O-ring sufficiently, leading to slow pressure drops.
• Clogged Dip Tube/Spunding Valve (Corny Keg): When dry hopping directly in a Corny, hop particles can clog the dip tube during transfer or the spunding valve during fermentation. Using a hop screen or bag can mitigate this, but it adds to the already challenging dry hopping process in a Corny.
• Krausen & Blow-off Issues: While steel is easier to clean, exceptionally vigorous fermentations can still push krausen into your spunding valve or blow-off tube. For high-gravity beers, I always start with a blow-off into a bucket of sanitizer for the first few days, then switch to the spunding valve.
• Inaccurate Pressure Readings: Cheap spunding valves can be unreliable. I always cross-reference with a known accurate gauge or use a trusted brand. An inaccurate reading can lead to under- or over-pressurization.

Sensory Analysis: The Impact of Steel Fermentation

Fermenting in stainless steel, particularly under pressure, has a distinct impact on the final beer’s sensory profile. This isn’t just about convenience; it’s about control and quality.

• Appearance: My beers fermented in steel are consistently clearer, especially with cold crashing under pressure. The higher pressure helps compact the yeast and trub, and the closed system prevents oxidation haze. I often achieve near-commercial clarity without fining agents.
• Aroma: This is where pressure fermentation really shines. By fermenting under 0.5-1.5 BAR (7-22 PSI), I can suppress ester production, leading to cleaner, crisper lagers and pilsners. For IPAs, fermenting under pressure, especially when dry hopping, drastically reduces hop aroma loss and creates a more vibrant, fresher hop character. My experience is that volatile hop compounds are better retained.
• Mouthfeel: Pressure fermentation leads to naturally carbonated beer with very fine, stable bubbles. This results in a softer, creamier mouthfeel compared to force-carbonated beers. The ability to transfer beer under pressure also means minimal CO2 breakout, preserving this delicate carbonation.
• Flavor: The most significant impact I’ve noticed is the cleanliness. Reduced oxidation from fermentation to serving means no cardboard or sherry off-flavors. Lagers are exceptionally crisp and clean, while ales retain their malt and hop character without being muddled by unwanted fermentation byproducts or oxidation.

FAQs

Can I ferment a full 19L batch in a Corny Keg safely?

While a 19L Corny keg has a nominal volume of 19 liters, I strongly advise against filling it completely for fermentation. You need adequate headspace for krausen formation and CO2 accumulation, typically 10-15%. This means for a 19L Corny, I recommend fermenting no more than 17 liters of wort to avoid messy blow-offs and maintain a safe pressure environment. Overfilling also significantly increases the risk of krausen clogging your PRV or spunding valve.

What is the benefit of the Kegmenter’s thermowell?

The integrated thermowell on the KegLand Kegmenter allows for a temperature probe to be inserted directly into the wort, providing a highly accurate reading of the actual fermentation temperature. My experience is that external temperature probes (taped to the outside of a Corny keg) can be off by several degrees from the internal liquid temperature, especially in a temperature-controlled chamber. This precision control with the thermowell enables me to consistently hit target fermentation temperatures, crucial for controlling yeast behavior and ester production, leading to more repeatable beer quality.

How do I dry hop effectively in a Kegmenter without oxidation?

One of my favorite methods involves a “soft crash” and pressure release. After primary fermentation, I’ll crash the beer to 2-4°C (36-39°F) for 24 hours. This compacts the yeast. Then, I’ll slowly vent the pressure through the spunding valve. Once ambient pressure is reached, I open the large lid, add my dry hops (often a hop sock to prevent clogs), re-seal, and re-pressurize the headspace with CO2 to about 0.5 BAR (7 PSI). I then bring the temperature back up to a “warm dry hop” range of 16-18°C (61-64°F) for 2-3 days before cold crashing again. This minimizes oxygen exposure while maximizing hop extraction. Remember to regularly check for new techniques and equipment on BrewMyBeer.online.