A Simple Yeast Catcher

Written by VP of Communications on . Posted in DIY Articles

Yeast is one of the most expensive ingredients brewers use to make beer. High quality yeast can run from a couple of dollars for a dry version, to up to $10 for a Vial from White Labs or a Smack Pack from Wyeast. I would say that yeast probably calculates to be the most expensive ingredient per gram.

To cut costs on a brew day, a lot of homebrewers like to use reclaimed yeast from previous batches of beer. If you're making a beer that is of reasonable gravity, this yeast likely won't be too stressed and mutated, and can be easily "re-pitched" on future batches. You can re-pitch yeast a multitude of ways, one being to simply transfer your wort onto your previous batches yeast cake. You are ensured an extremely large quantity of yeast and your beer should begin fermenting immediately.

Another method (which we won't fully get into on this post) is to "wash" your yeast. This basically involves boiling water, cooling it down, and then creating a slurry of material from your past-batches yeast cake. The layers will stratify into beer, trub, and viable yeast. You can then decant the stratified layers and isolate the layer of yeast and use that in future yeast starters.

Since this is a DIY Gadget article, let's talk about another method that is not only super easy to implement (versus washing yeast), it's also super inexpensive to build! Let's get into the parts you'll need:

  • Two 3-piece airlocks (Link) - $1.05/each
  • One Mason/Ball Jar - $??/Free if you have one laying around
  • Two Rubber Grommets (Link) - $0.35/each or Free if you have some on old buckets
  • One 3' x 7/16" Vinyl Tubing (Link) - $0.45/ft.
  • One 3/8" Drill Bit

This method, while very effective in catching yeast at high krausen (which is the healthiest yeast you can ask for), isn't always going to produce results. This DIY yeast catcher will only work if your beer "blows off". If you've been brewing for a while, or have ever brewed a high gravity beer, you've probably experienced a blow off. It's when your krausen goes so high due to the fermentation process, that it escapes your carboy or bucket and muddies up your airlock, or worse, makes a huge mess in your fermentation area.

Smaller gravity beers, or batches where there is ample head space in your fermenter likely won't cause a blow off, and this method won't apply to those situations. Also, if you have made it a habit of using a product like Fermcap, this method won't generate the results you desire. Regardless, even if you don't get a blow off, this gadget will still provide you with a usable airlock, in case you do happen to get a blow off. As such, I use this every time I brew because I don't want to have to clean up a mess in my fermentation chamber. Now lets get to building this thing!

To start, take the lid of your Mason or Ball jar and drill two holes each about 1/4" from the edge with a 3/8" drill bit, like so:


It's important to note that this metal is very thin, and can easily be ripped or torn, causing the hole to not be a perfect circle. If you have a step bit, or a fine toothed hole saw bit, I would recommend that rather than a paddle bit. I would also recommend cleaning up the holes with a metal file of some sort to grind off any barbs that may have been cut in the process. No worries if you messed up the holes on your first go-round -- these lids are pretty easy to come by.

Next, after you've dulled the holes with your file, install your rubber grommets.

Now let's turn to the first airlock we'll use. We only need the body of the airlock, so you can keep the lid and the "bubbler" in your brewing storage drawer. Take your vinyl tubing and heat one end up in boiled water so that it becomes very flexible (don't burn yourself!). Take that end and fit it over the airlock's vent tube. Take the other end, and squeeze it into one of the holes you drilled into the jar lid.

Clean and sanitize EVERYTHING! Get sanitizer into your tubing, as well.

Next, take your second airlock and assemble it like normal, and insert it into the remaining hole on your jars lid. 

Finally, install the components so that your jar basically acts as an airlock off of your fermenter, and you will catch any yeast that is blown off!


That's it! Pretty easy, and should only cost you around around $5.


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