For as much as I love hoppy beers, dealing with all the hops throughout the process can be challenging. Racking to a serving keg or bottling bucket from a primary fermenter full of loose hop pellets has its issues. Dry hopping in kegs and dealing with clogged poppets or a hop bag blocking the dip tube isn’t fun either. I’ve tried sinking fine mesh hop bags with stainless steel washers. I’ve tried hanging bags of hops with floss inside a keg. I’ve tried ramming tea balls with hops. I’ve even gone the pantyhose route. For racking, I’ve tried dry hopping loose in primary and putting a mesh bag over the racking cane or just bagging the hops in primary. All of these methods work OK, but I wanted a more reliable solution that allowed me to dry hop loose both in kegs and during primary fermentation.

My worst experience dealing with hops and another reason I wanted to find a solid dry hopping solution came from transferring a NEIPA to a serving keg with loose hop pellets too early, which resulted in additional fermentation in the serving keg, which led to krausen inside the full keg which clogged the carbonation stone and the pressure relief valve. The additional fermentation also moved around the loose hops enough to get inside a filter I was experimenting with clogging the liquid out line. So I couldn’t release the pressure via the clogged pressure relief valve or through the C02-in poppet (because of the clogged carbonation stone), and I couldn’t pour beer through the clogged out poppet. This was the result…

Auto Siphon Filter

I’ve tried and didn’t like the mesh bag over the siphon approach. Mainly, the bag had a tendency to want to float it’s way off the end of the siphon. For awhile I would secure the bag to the siphon with a worm clamp, which worked alright, but was another step and I started losing track of which bags I used for dry hopping in sour beer and which I used for clean beers. I figured a stainless solution that was easy to clean and sanitize would be a better racking solution so I purchased a 300 micron stainless steel filter intended to be used to fill with dry hops and shoved into a glass carboy, only I would slide the auto-siphon inside the filter and cap the other end of the filter with the plug, which would allow me to stick the siphon in the fermenter and rack without issues. [The 300-micron filters are intended to be used with hop pellets and the 400-micron filters with whole leaf hops, I would recommend going with the 300-micron filters to use for both.]

This is the glass carboy dry hopper, notice the red silicone cap that sticks out from the bottom.

Although this does work, it wasn’t without problems, the rubber stopper on the end sits up too high above the last gallon or so of beer your racking out, which meant I would have to tilt my fermenter towards the siphon to compensate. The other issue is that these filters are only 1″ inch in diameter, which is too narrow to fit over the fattest part near the bottom of the siphon without rubbing and likely scratching the siphon, which could lead to infections down the road.

Since I purchased this particular filter from the online store at Utah Biodiesel Supply, I thought I’d reach out to them to see if they were open to slightly adjusting their dry hopper for glass carboys product into an improved auto-siphon filter. Turns out they were more than willing to help out and super cool to work with. We came up with a custom 300-micron stainless steel filter that is wide enough to easily slip over the racking cane without scratching it (1 1/8″ diameter) and has an enclosed inverted bottom, which means it sits flat against the bottom of your carboy when racking and eliminates the need to use the red rubber stopper used with the glass carboy filter, thus eliminating the tilting of the fermenter. The original test filter I purchased was 18″ inches to ensure it always sat above the beer you were racking, but as described below in the keg hopping section, was increased to be 21″ to create a multipurpose filter.

New custom made auto siphon filter w/ enclosed flat bottom and increased to 21″ and larger diamater to prevent scratching of siphon

Keg Filter

If you can dry hop in fine mesh bags inside kegs, then why even worry about loose dry hopping? One of the interesting things I learned when doing research for a post on hopping methods, was from a Hopsteiner study that tested the extraction of dry hopped beers with pellets loosely vs. dry hops contained in a finely woven sack. A lab trial was conducted to test whether using a finely woven sack reduced the solubility of the hops. Two separate green beers were dry hopped, one loose and the other in a sack. They found that the hops that were floating loose in the beer tested with almost 50% more linalool than the beer with hops in a sack, which they concluded could “increase the likelihood of a beer with a more intense aroma.” 1 In theory I can see how this makes sense, it’s kind of like taking a large bedspread out of the clothes dryer that appears to be completely dry, but until you lay it out across the bed do you realize the entire middle section is still wet. If you could, you would get a higher drying efficiency of the bedspread if you didn’t have to crumple it up into a ball to fit it in the dryer, similarly the study suggests you may see greater extraction from hops if they aren’t crammed in a mesh bag.

The potential for greater extraction from hops, while reducing the total amount of hops used, was enough to convince me to find a way to dry hop in a kegs and fermenters loose. Searching online for possible solutions, I found the greatest potential in a method created by Derek Dellinger at Bear-Flavored.com [link to article]. I thought his idea to alter the use of a fine stainless steel corny keg dry hop filter intended to be filled with hops and capped but instead used to go around the dip tube and allowing the hops to float free inside the keg was brilliant.

Different size corny keg dry hoppers available

As you can see from the picture above, the stainless corny kegs dry hoppers come in various sizes, I started out by purchasing a 21″ inch one, thinking the higher the filter sat in the keg, the less likely hops would find their way in. I drilled a 3/8 hole in the lid of the screw on lid that comes with the filter with a step bit using one of the holes already in the lid as my starter hole. If you want to go this route (which I don’t recommend now) there are two things to keep in mind when drilling the hole yourself. The first is the center of the hole should be about 5/16 from the center of the lid. This is because if you drill a hole directly in the center of the lid, you will have a hard time getting the filter to align with the dip tube in the keg, which can make it difficult to get the dip tube to fully seat. The second thing is there is an inner stainless steel mesh screen on the inside of the screw cap that you have to support from underneath when drilling or you will rip it from the soldered joints with the force of the drill pushing down on the lid (I ruined one cap this way). I’m sure there is a better way to do it, but being there was an empty beer bottle next to me, I just used this to drill the hole at the same time supporting the mesh screen.

Now, I could slip dip tube through the drilled hole in the corny keg filter and dry hop loose around the filter and it worked (kind of). I used this filter for two kegs with no real issues, the filter kept the hops out and I had very minimal hop debris in my glass during the first couple pours. Because of the success of this, I decided I needed more of these for my other kegs, so I purchased a 2-pack of the shorter 11.5″ filters and drilled holes in the caps as described above. These shorter filters were cheaper and seemed to work fine for the first two kegs I used them on, but I was getting a lot of hop debris in the first 4-6 pours, which somehow made its way into the space between the dip tube and the drilled hole, or through the filter itself, which seems less likely. This isn’t a big deal, but still, that’s kind of a waste of beer, you can drink these pints if you don’t mind flossing hop debris out of your teeth (they taste aggressively raw and bitter). It also seemed that if some fermentation was still going on inside the keg or restarted after being racked into the keg, this would make the problem even worse by moving around the hops so much that some found their way inside the filter.

This is the 21″ stainless corny keg dry hopper, which goes nearly to the top of the keg

The third keg into using these shorter 11.5″ filters, I started having clogged poppet issues from the first early pours. If you’re lucky, the collection of hop debris in these early pours won’t clog and eventually you will get clear pours, but you’re not always lucky. Another downside of this dry hopping method is that the drilled hole in the cap was sharp enough to scratch the dip tube when sliding it into place. So although these filters seemed to work most of the time, they weren’t perfect. I decided to again reach out to Utah Biodiesel Supply to see if we could come up with a better solution.

This is the 11.5″ stainless corny keg dry hopper

My Favorite Dry Hop Method

At first, we experimented with having corny filter caps come pre-drilled when using the shorter corny keg filters, but I occasionally ran into the same problems with early pours being filled with hops and although I didn’t get a clogged poppet, it was definitely on my mind early on in a kegs life. What we ultimately came up with was to extend the length of the newly created auto siphon filter to 21″ from 18″ to allow the filter to extend almost to the top of the keg. You can then insert a #6 or #6.5 pre-drilled stopper (#7 stoppers are too big) into the filter and slide the dip tube through the stopper and into the filter, which seals up the filter from rouge hops. I would suggest avoiding the rubber stoppers that have an intense rubber smell to them (weirdly the same aroma I get from some sour beers). Instead, look for the silicone stoppers, or just give them a good sniff before buying! You might still get a little bit of hops in your first couple pours, but if the debris was small enough to get into the filter somehow, it shouldn’t be large enough to clog your poppet.

Final Solution to Dry Hopping Loose

So after way more trial and error than you likely wanted to read about, the final filter I recommend getting is this new dual purpose keg hop and auto siphon filter, that Utah Biodiesel Supply sells for $35. I even use it in a 10-gallon keg I use for fermenting hoppy beers, which allows me to dry hop loose in the keg and make transfers without clogging poppets. I should note that I do not have any financial interest in these filters, I’m just happy they were willing to deal with me (since July) to come up with a product I think works great for dealing with hops!

Final Version of the Filter

One thing I should say, it’s possible you might find when using one of these filters that you have a hard time pressing down your dip tube all the way into the keg because there needs to be enough room between the keg bottom and the dip tube for the filter to sit. If you run into this situation, I’ve found the easiest solution is to clip just a tiny bit off the end of your dip tube. I’ve tried a number of ways to do this and by far the easiest way is by using a small mini pipe cutter. It’s extremely easy to do and will cut perfectly without scratching anything. I purchased the pipe cutter for about $5 from Harbor Freight (http://www.harborfreight.com/1-8-eighth-inch-to-1-1-8-eighth-inch-tubing-cutter-92878.html). You may not have to do this, but just in case anybody is afraid they are putting too much pressure against the bottom of the filter when pushing in the dip tube, this is a good fix. I actually just had to use this pipe cutter to fix a replace a bad washing machine valve, who knew that homebrew toys had real life value!

[Update 9.13.2017] I had intermittent problems with my fermenting 10-gallon keg not pushing beer out with a filter around the dip tube. It turned out that even though the filter seemed to have enough room to fit around the dip tube and have the gas ball lock seat properly, the dip tube was pressing against the screen and the bottom of the keg too tightly to dispense. As a precaution, it probably doesn’t hurt just to go ahead and cut a little bit off your dip tube.

Footnotes

  1. (W. M., & S. C. (2013). DRY HOPPING – A STUDY OF VARIOUS PARAMETERS. Retrieved from http://hopsteiner.com/wp-content/uploads/2014/03/Dry-Hopping-A-Study-of-Various-Parameters.pdf)
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