How to Build a Hop Filter

Home beer brewers use a hop filter to extract hop sediment from wort, which is the liquid extracted during the mashing process while brewing beer. The filtration of the hops and hop sediment is crucial to regulate hop content and to achieve a desirable level of clarity in the beer.

Traditionally, home brewers have accomplished this with relative success using a stainless steel mesh strainer, such as those used in cooking. Nevertheless, more recently, home brewing has grown more sophisticated, and the domestic brewmeister has begun to experiment with arrangements that are far more complex.

We should start by noting that when it comes to hop filters, “right” is a matter of much debate. Some prefer inline filters, those at the center of the system, while other enthusiasts prefer their hop filter on the sucking end or the pouring end. All of these configurations have pros and cons, and they all have clogging issues, albeit to different degrees.

To avoid clogging, there is no better method than the mesh strainer. Still, we prefer the inline hop filter, and the remainder of this article with deal with a simple yet modern design of that style. Nevertheless, home brewers may want to explore all three configurations, so that they can weigh the pros and cons of each and decide which one best suites them.

We prefer the inline hop filter because it provides the best level of filtration. The downside to removing all of that additional material is that the system clogs much faster than the others do. Left unattended, common inline filter designs will completely clog before even 5 gallons have passed through. Therefore, brewers should expect to have to switch the filter halfway through the process. Of course, the alternative is to build or purchase a heavy-duty unit, but that is beyond the scope of this article.

When most enthusiasts refer to clear beer, they are referring to hop sediment of less than 5 microns. Most professional brewers will filter at 5 microns and then at 0.5 microns. Some go to 0.3 microns for shelf stability. The home brewer should target at least 5 microns with a single-pass system, but you can go lower. However, it’s not practical to go any lower than 1 micron.

You’ll also need a pressurized system, so let’s consider a common configuration:

• Two sanitized kegs including gas hook-ups
• CO2 tank and regulator
• 4 hose clamps minimum
• 12 feet of surgical tubing
• High-grade filter with the appropriate housing
• Plumbing fittings and nylon reducers to interface beer lines

This guide assumes an intermediate level of proficiency, so we’re going to skip directly ahead to the filtration aspect of the system. You’ll want to use a low-end water filter, such as those used for whole-house systems. You want quality, but you don’t need all the extra capabilities of the high-end models. You can find appropriate filtration systems in almost any hardware store. They will generally cost less than $50, but it depends greatly on which fittings it comes with it.

Ensure that the unit you purchase filters down to 5 microns at least. However, as mentioned earlier, feel free to purchase one that provides a finer level of filtration. In addition, make sure that you purchase appropriate fittings for that filter that will allow you to interface it with the beer lines. Once you’ve done that, there’s just a few extra steps to incorporating it into your current configuration.

1. Determine the distance from the inline filter position to each side. Add some slack, and ensure each side is equal. Now cut two stretches of surgical tubing, which you will use as in and out lines for the filter.

2. Install a fitting at the end of surgical tube. By using a keg-out fitting at one end and a beer-out fitting at the other, you can create a system that allows uninterrupted pass-through from the source keg through the filter to the collection keg.

3. You’ll need to prepare a garden hose, preferably one used solely for this purpose. You’ll use it to back-flush the filter when you’re finished.

4. After back flushing the filter, sanitize it, and then store it in a freezer. Doing so maximizes the life of the filter, and it will allow you to get 100 gallons or more out of it before having to replace it.