HopBlock: The Hop Filter We Built Because Mesh Filters Kept Failing

I designed the HopBlock in 2019 because I was tired of hop filters that did not work, including the one I used to ship with the Unibräu. Six years later it is still the part I get the most thank-you emails about, so here is the original story, updated with what we have learned since.

The problem with mesh

The early Unibräu came with a 400-micron stainless mesh filter, about ten inches deep. It held a couple of ounces of hops and it was gone from the kit within a year. The mesh ripped, it clogged, and the utilization was terrible: hops packed into a tight cylinder do not give up their oils to the wort. To brew a double IPA I needed four of them, and I was buying more hops than the recipe called for to make up for what the filter wasted.

Every mesh filter and hop spider on the market has the same limits. Fine enough to stop pellet debris means fine enough to clog. And the more hops we all throw into the whirlpool, and the trend has only gone one way, the worse it gets. The other thing customers kept asking was how to get the last of the wort out of the kettle without tipping it. Two problems, one part.

What the HopBlock is

A 10-inch disc of perforated 304 stainless with a silicone seal around the edge, sitting on the floor of the kettle. The wort passes down through it; the hops stay above. Below the plate is a dip tube that press-fits into the 1.5" tri-clamp outlet with its own silicone seals, reaching almost to the bottom, so the pump draws filtered wort from under the plate and leaves almost nothing behind.

The holes are the part that took a year of testing. Too fine and the plate clogs like a mesh. Too coarse and pellet sludge reaches the fermenter. The size we settled on holds both pellet and whole-leaf hops and lets the wort through at full pump flow with a heavy hop load. Some pellet dust gets through. It is a filter plate, not a membrane, and that is the trade that keeps it flowing.

What changes on brew day

• Hops go straight in the kettle. No bags, no spider, no cylinder. First wort hops, boil additions and whirlpool additions all go in loose and stay in contact with all the wort. Utilization goes up, so if you move to a HopBlock from a spider, expect the same recipe to taste more bitter and more aromatic.
• The pump does not choke. Recirculate during the whirlpool as long as you like. The plate has about 25 times the open area of a mesh spider.
• The counterflow chiller stays clear. This is the one people notice most. Hop debris in a counterflow chiller is the usual cause of a transfer slowing to a trickle. With the plate between the hops and the outlet, it does not happen.
• If flow does slow, drag a flat spoon lightly across the plate during the boil. It clears in a second. Try that with a mesh bag.
• You get all the wort. The dip tube reaches the bottom, so there is no tipping the kettle at knockout.

Fitting it

The HopBlock is built for Unibräu systems and our tri-clamp brew kettles. It drops in before you mash, sits under the grain basket, and stays in for the whole brew. Cleaning is a rinse and a soak; the plate comes out in one piece and there is no mesh to unpick hop matter from. It comes with the pickup tube, or without it if you already run our dip tube / whirlpool arm.

What it is not

It is not a fix for a bad whirlpool. Give the whirlpool ten minutes to settle before you open the outlet and the plate has less to do. And it is not a bottle-clear filter: expect a little pellet dust in the fermenter, which the cone of a conical fermenter drops out in the first day anyway.

Ready? The HopBlock is here. If you run a kettle we did not build and want to know whether it fits, send us the kettle diameter and the outlet fitting.