This is a collection of information about the BrewCap inverted carboy fermenter developed by Kinney Baughman. Most, if not all of this information, was originally posted here by Kinney. Information about the BrewCap and other brewing devices can be obtained from Kinney via email to:


The main idea behind the BrewCap is that it gives the brewer a means for removing the yeast directly from the bottom of the fermenter. This is advantageous for a number of reasons:

  1. It saves racking to secondaries, priming, and ageing tanks and the clean-up time that goes with it.
  2. It reduces the risks of oxidation and contamination.
  3. It allows for a built-in blow-off system to eliminate the bitter resins that form on the kreuesen head.
  4. The BrewCap can act as a yeast propagation chamber. If you're using pure yeast cultures, you can drain yeast directly from a fermenting batch of beer into a batch of fresh wort, getting maximum mileage from a package of yeast without culturing agar slants. You can also drain the yeast into a "yeast bank" yielding over a dozen starter cultures from a single batch of beer.

Now on with the show....

                        The BrewCap
                    /   head space     \ 
                   |     ||             |
                   |     ||blow off     |
                   |     ||  tube       |
                ___|     ||             |_
               |   |     ||             | | <- stand
               |    \    ||            /  |
               |     \   ||           /   |
               |      \   \\         /    |
               |       \   \\       /     |
               |yeast ->\---||-----/      |
 Blow-off      |level    \  || || /       | 
  hose         |_________  (|| ||) _______|         Carboy neck and
  |            |           (|| ||)  <-------------  BrewCap
  |            |            -----         |
  |         ___|            || ||         |
   -----> // - \\          //   \\        |
       __//__  |\\        //      \\   <----------- Yeast Collection
      |  ||  | | \\      //         \\    |             Hose
      |--||--| |  \\ ___//            \\  | ____
      |  ||  | |    \---/               \\||_  _|    <- Yeast draining
      |______| |            BrewCap       \\_||__        valve
                                           \_____|       (not to scale)
   bucket of water

Comments on a recent r.c.b. thread...

I've had several private email queries about the BrewCap. It seems there is still some confusion as to how the little gadget works. Allow me to summarize and comment on the recent r.c.b. thread.

Ken Sullivan sez:

I can't help but try to provide a better understanding of the brewcap:-) Imagine if you will, an upside down glass carboy resting in a wooden stand. The orange carboy cap is tie-wrapped on so it doesn't come off spilling all of your precious wort on the floor.

(See illustration above)

First: The BrewCap is not the orange universal carboy cap. The holes in the orange cap aren't big enough to provide for safe expulsion of the CO2 gases. Besides your beer would pick up a plastic taste if you use the orange cap.

A blow off tube runs from the top (was bottom) of the carboy head space, sucking off all that nasty krausen and DMS and stuff, down through the carboy cap and into a water-filled bucket. You could also put an air-lock on the blow off tube. Now there is another tube which is just barely inserted through the carboy cap, this tube has a clamp on it, and allows one to drain the trub and dead yeasties.

Then Dave Jones writes:

Ok, if I remember right, this Brewcap thing uses an upside down carboy. How does CO2 escape from an upside down carboy?

Followed by Steve Bernholtz's question:

What about the krausen(bad spelling)? Just leave it like without the blowoff?

The "blow-off tube" that extends up into the head space above the fermenting beer (see drawing above) gives a path for the CO2 gases to follow out the BOTTOM of the carboy, through the carboy neck. A 1/2" hose, 3' long, is attached to this tube. The end of this hose can be submerged in a bucket of water during primary fermentation to collect the kreuesen head and CO2 gases. Some of the excessively bitter resins will collect on the bottom of the carboy. They'll stay there, safely out of the way of the beer. During secondary fermentation, you can remove the hose from the bucket and form it into a "U" shape and fill it with a couple inches of water. The hose then becomes its own water trap.

Jeff Ely writes:

He (Dave Miller) refers to a piece of equipment called a Brewcap. Is this the rubber carboy cap with two raised openings that my friends were using? Is this a common alternative to Miller's suggestion?

It is an alternative to racking to secondaries and priming tanks per many authors' suggestion.

What is the purpose of Miller's recomended transferring of the wort to and from the carboy?

To separate the beer from old, decomposing yeast and sediment.

What about this alternative method makes that transferrence unnecessary?

It saves time and eliminates the chance for oxidizing the beer and picking up bacterial contaminations in the transfer. Also, if you're too busy to bottle or keg when the beer is finished, you can leave the beer in the fermenter as long as necessary. I've left beer in an upside down BrewCap for 2 or 3 months and still came out with clean tasting beer. All the yeast and trub has been removed so it's no different than storing beer in bottles.

Another thread from a couple years ago...

(Tom Maszerowski) moscom! writes:

Even with this, it is not simple task to turn over 5 gallons of wort in a carboy, you may want help.

Hmmm. If you held the carboy up in the air and tried turning it over all in one motion then I would agree. Fortunately, that's not the way to do it. Instead, from its upright position you tip it over and lay it down on its side on the floor or counter and THEN tip it up into its upside down position.

(Tim Phillips) tcp@phobos.ESL.COM observes:

when emptying the trub or filling the bottles, the long tube (i.e. the fermentation lock) is going to suck a lot of air. It's probably best to take the lock off temporarily.

This is a point many people make. Yes, you do suck in air but the important point here is that CO2 is heavier than air and the CO2 blanket formed during fermentation for the most part shields the beer from the O2 coming in. Even if it doesn't succeed totally, since you aren't swishing the beer around the risks of oxidation, which is the concern here, is really quite minimal. In fact, it's no more a problem with the BrewCap than it is with siphoning from a carboy standing right side up.

I've NEVER had an oxidation problem from fermenting with this system.

Any ideas on how to do blow-off with this method? In case of clogging, is an upside-down beer volcano better than right-side-up (e.g. the floor is easier to clean than the ceiling :^)?

No one, to my knowledge, has ever blown up a carboy using the BrewCap. The reason being the blow-off tube is a 1/2" in diameter. By siphoning the wort into the carboy using a 1/4" ID siphon hose, nothing large enough to clog the larger 1/2" tube will ever get inside the carboy. Relax, don't worry, etc., etc.!

While we're on the subject, the whole issue of volcanic carboys arose because Charlie Papazian in TCJHB says you can put a stopper in a carboy and blow off through a 1/4" ID siphon hose. As hundreds of beer volcanoes around the country will attest, sooner or later you'll get burned if you keep using that technique. When Dr. Michael Lewis suggested the blow-off method almost ten years ago, he recommended blowing off through a 1" ID clear plastic hose stuffed into the neck of the carboy. NOTHING clogs one of those suckers! The 1/2" tubing employed by the BrewCap is a compromise on the 1" hose but we've found it to be sufficient. I wish Charlie would modify that part of his book but he'd rather ignore the issue for some reason. That has always puzzled me because Charlie has done more than anyone to spread the word on sound brewing practices.

(Ken Giles) keng@epad.MENTOR.COM talked about the difficulty of trub removal:

The biggest problem we had was with the settling trub sticking to the shoulders of the inverted carboy. The instructions for the BrewCap warn you about this, recommending that you rotate the carboy quickly back and forth about its vertical axis in order to dislodge the trub. This was only moderately successful. I estimate that 1/4 of the trub could not be removed because of this problem.

1/4 of the trub is indeed excessive and I'm hard pressed to say why that was your experience. Did you use a wort chiller? I do and have always been able to remove virtually all the trub and yeast sediment. I've never fretted over a couple of tablespoons of residual yeast. Obviously you were left with more than that. I'd like to hear from more brewers who have had this problem. It's one that keeps cropping up yet is one I've never had.

Using an upside down carboy was a compromise over the ideal shape for the kind of fermentation system we were shooting for. A cylindro-conical vessel would be ideal but who could afford the tooling required to make one of those monsters? Carboys are relatively easy to find and are made of glass which are easy to clean and sterilize. Designing a cap to fit carboys, therefore, was the difference between just having an idea and having an idea you could share with everyone else. The shoulders of the carboy do tend to collect sediment more than we would have liked, thus the sharp twisting back and forth action that Ken wrote about. But when done regularly, and that means from day one, we always found it to do the trick.

As for hop pellets, don't be lulled into thinking they're nothing but powder. Upon rehydration, pellets can be found to contain whole leaves which would have a real impact on the way the BrewCap operates, especially when it comes to draining away the sediment. I suspect hop pellets are the cause of many of the complaints we've heard about not being able to drain the BrewCap properly. We use whole hops and strain through a copper wound pot scrubber enveloped in a fine mesh hop bag, both of which are attached to the bottom of the pick-up tube. This gives a remarkable clear run-off into the fermenter.

I see why loose hops would be a problem (unless) you use a hop bag. Dry hopping does seem impractical, though.

Dry hopping is a pain but it can be done if you tie the hops up in a fine mesh hop bag or a piece of ladies nylon hose and stuff it in after primary fermentation. The bag floats to the top of the fermenter, below the blow-off tube and out of harm's way.

This problem of dry-hopping in the BrewCap has puzzled me for years. Recently I came up with a little homebrewer's sized "hopback", though, that seems to have solved the problem. It imparts the hop nose of dry hopping with none of the hassle, whether one is using a BrewCap or a 'normal' fermentation system, but that's a topic for another discussion.

(Oran Carmona) writes:

The system itself works very well for the most part. My major complaint with it is that when you use it with a 5 Gallon carboy, you tend to lose anywhere from 0.5-0.75 gallons in the process of draining off the spent yeast/trub.

Not really. This is another complaint we often hear and is the result of the mere PERCEPTION of lost beer rather than any ACTUAL loss of beer. It's just that when one uses the BrewCap, for the first time you see just how much yeast and trub is deposited during the course of a normal ferment! Sure, when you're draining that yeast away it appears you're losing a lot of beer as well. This is especially true with the BrewCap because you can see the level of the beer drop as the yeast is removed. But you either drain it away using the BrewCap or leave it behind in a regular fermenter. Either way, you lose it. I've done careful experiments just to see how much beer is lost from draining the yeast. This is a simple matter of collecting all the spent yeast into a jar for the entire ferment. I usually lose about 1/3 Cup of beer. Most people leave at least that much behind when racking to secondaries and/or primaries. So to the contrary, I've found that you actually lose *less* beer using the BrewCap than with a conventional system. (Some beer is lost during blow-off, of course, but I'm assuming everyone expects to lose beer when using a blow-off system.)

A BrewCap FAQ

Q: How much pressure does 5 gallons of beer put on the BrewCap?

A small lesson in hydrostatics is always pertinent when talking about the BrewCap. It was as surprising to me as it is to many people to discover that 5 gallons of beer which weighs nearly 50 pounds does not generate 50 pounds of pressure. Water pressure is a function of the depth of the liquid in a container and not its weight. The rule of thumb here is a 3' column of water generates 1 psi of pressure. Since 5 gallons of beer in a carboy is less that 3' tall, less than a pound of pressure is put on the cap. A negligible amount. The cap comes with a releasable wire tie for the faint of heart! Though I don't/can't recommend it, I normally don't use the wire tie on my carboys.

Q: How do you add priming sugar to the BrewCap?

A: This procedure remains one of the more surprising aspects of brewing with the BrewCap. I didn't discover it until after I'd been brewing with the gadget for about a year.

Boil your priming sugar and water solution on the stove. Cool. Place on top of the inverted carboy. You will have already drained all the yeast from the yeast collection hose. Bring the hose up and place the yeast drainage valve down into the pan of priming sugar solution. Open the valve and the priming sugar, by the laws of siphoning, will automagically flow into the bottom of the carboy! Turn off the valve. Lay the carboy on its side. Then re-invert it to its right-side up position. The blow-off tube is made of a semi-rigid plastic and can be used as a spoon to stir the priming sugar into solution without removing the cap. When you're satisfied the priming sugar is well-mixed with the beer, reinvert, add a bottling wand and bottle. Beats the hell out of siphoning to a priming tank, believe me!!

Q: How do you make a stand for the carboy?

A: Two simple stands are described in the instructions. Here's a brief outline: Take 2 buckets or 2 plastic milk crates. Cut a 3-4" hole out of the center of each bucket/crate. Wire and/or glue them together in such a way that the bottoms are touching each other ( the bucket/crate combo will then be open on each end.) Like so....

                  side view                         end view
     __________________________________           _____________
                      |                          |             |
                      |                          |     ___     |
                      |                          |    |   |    |
                      |                          |    |___|    |
                      |                          |             |
     _________________|________________          |_____________|
    ^^^              ^^^
  lip of          bottoms of 
bucket/crate    buckets/crates

With the carboy sitting upright on the floor, place the buckets/crates on top of the carboy, pulling the hoses and neck of the carboy through the holes you've cut. Lay the carboy/stand contraption down on its side on the floor and tip into the upside down position. Place the whole shebang on a counter.

I've also hung carboys from the ceiling with a macrame hanger.

One ingenious HBD'er constructed a stand out of a single piece of 2x4 and a length of rope.

Q: Where can I buy one? How much do they cost?

A: The short answer is to call your local homebrew shop. If they don't have one, tell them they need to carry them! (Small bit of commercial arm- twisting here!) They can get a wholesale brochure by writing:

BrewCo POB 1063 Boone, NC 28607-1063 (704) 963-6949

Suggested retail price these days is $13.95. That includes the cap and all the hoses, clamps, and valves necessary to attach it to a 5 or 6 1/2 gallon carboy. You provide the carboy, which most people already have anyway.

The BrewCap will not fit screw-threaded 7 1/2 gallon carboys since it's designed to snap onto the outside lip of unthreaded carboy necks.

If you have any further questions, please hit me with some email. I'd like to make this little information file as complete as possible.