Build a Randall-Style Hop Filter

randall-style hop filter in use
Photos by Christian Lavender

As a homebrewer and kegerator operator, I am constantly asking myself, “How can I make my draft brews hoppier?” I want that hop aroma to leap from the glass as soon as I open the faucet just like when you open a can or bottle of a favorite IPA. 

I use Corny kegs as my secondary (and sometimes tertiary) fermenting vessels when brewing. With the right timing and a spunding valve, kegs allow my brew to self-carbonate with the malt sugars left over from the main fermentation. I recognize oxygen as the enemy of hop aroma compounds. Once the beer nears the end of fermentation, I don’t want any oxygen to get near my beer. So I can add dry hops near the beginning of fermentation or again when I transfer into the keg. The problem with my process of conditioning and dispensing within a closed keg system is that there is not a good opportunity to introduce additional post-fermentation dry hops. So after some careful consideration, I decided that filtering hops within the draft system was going to be my answer.

I had read about the original Randall the Enamel Animal, a Dogfish Head Brewery invention, and many other different types of hop filter builds online and from friends, but I wanted to build a hop filter that was going to be kegerator-friendly, easy to detach and clean, and cost-effective. I call it a hop filter because that was the original intent of the device. But, just to be clear, hops aren’t the only thing that I can add to this filter system. If doing a porter, you can add some coffee beans and/or mashed cherries to the filter. How about strawberries and a vanilla bean with that creamy IPA? The nice thing is that if the flavor mix doesn’t work out, you haven’t ruined the entire keg; just take the filter off-line. Also, if you are ever pouring your beer at a beer festival, the filter can be a great talking point and allow you to basically add another beer to your pouring repertoire. 

But, just to be clear, hops aren’t the only thing that I can add to this filter system

After assembling the hop filter, getting it installed, and pouring my first homebrew, I have to say I could really taste a difference in the hop profile of the beer. The additional blast of hop oils just prior to hitting my glass made an impact. One small addition to the kegerator has made an already smooth operator into a smooth hoperator!

Parts and Tools

• GE Household Pre-Filtration System. Model # GXWH20S
• Brewer’s Edge® KettleScreen™ with 1⁄2-inch thread and 12 inches long
• 1⁄2-inch Male pipe thread to 3⁄8-inch male barb connector
• 4 small 3⁄8-inch O-rings
• 3 clamps
• 1⁄2-inch female pipe thread to 1⁄2-inch female pipe thread coupling
• 2 Firestone liquid posts with 3⁄8-inch female pipe thread
• 2 3⁄8-inch Male pipe thread to 1⁄2-inch male pipe thread reducers
• 2 3⁄4-inch Male pipe thread to 1⁄2-inch female pipe thread bushings
• 2 Quick disconnect fittings for ball lock kegs with 1⁄4-inch MFL (threaded)
• 2 1⁄4-inch swivel nut to 1⁄4-inch barbed end sets
• 4 ft. of 3⁄16-inch inner dimension PVC tubing
• Teflon tape
• Filter wrench
• Adjustable wrench
• Flat head screwdriver
• Metal snips
• Measuring tape
• Bolt cutters