How to Build a Hop Filter

A hop filter is a tool that can be used to filter hops and hop sediment from wort, hot or cold, thereby ensuring a clear, sediment free beer with a regulated hop content. Most home brewers have been doing this the old fashioned way, with a stainless steel mesh cooking strainer, but brewers are experimenting with straining out hop sediment using stainless steel mesh in a variety of configurations. Some designs are affixed to the sucking end of the racking cane, some to the pouring end, and some in the middle, as an in-line filter. Most designs tend to be stymied by the clogging action effected by the hop sediment. We will look at a more modern design for the inline hop filter.

How to Build a Hop Filter

For whole hops and hop pellets, really there is no better way to filter than to use the household stainless steel mesh strainer. You can experiment with affixing various formations of stainless steel mesh to the end of your racking cane or suction tube for the big stuff, but using the old fashioned technique of pouring through the strainer will probably be the most efficient use of your time. After this step, a 5 micron filter can be used to get out all sediment, hop or otherwise, from the beer. We will describe a technique for making an inline filter to remove hop sediment during the racking process.

Inline hop filters tend to work the best, and also have the worst problem with clogging. Most designs will clog well before 5 gallons have been pumped out of a keg. Inline filters are very good at filtering, helping to make beer much clearer with each racking procedure, but you should be prepared to switch filters half way through the process – unless you make or buy a really heavy duty one.

If you want to get your beer very clear (down to 5 microns or less) you are going to have to use a pressurized system in order to filter it. To build one, you will require the following parts:

1. A high-grade filter with the proper housing,
2. Plumbing fittings necessary to interface with your beer lines (Nylon reducers and fittings to get from 3/4" NPT to 1/4" hose barb. You may have to use a 3/4" NPT to 1/2" NPT and then step down with a 1/2" NPT to 1/4" hose barb fitting.
3. For cleaning and back flushing - these will be the brass 3/4" NPT male to garden hose male adaptor, and brass 3/4" NPT male to garden hose female adaptor.
4. Some extra beer line surgical tubing (about 6-10 feet)
5. Hose clamps to fit your beer lines (4 at least – always good to have more)
6. A CO2 tank and regulator,
7. Two clean and sanitized kegs with gas hook-ups.

The filter is the part that stymies most folks. It is recommended to use a low-end water filter designed for filtering tap water for the whole house. These are available at most hardware stores in the plumbing section. The Omni Company makes your basic whole-house filter which sells for around $36, depending on which fittings come with it. This unit filters down to 5 microns. While you are in the plumbing section, hunt around for the right series of fittings that will allow the filter unit to interface with your beer lines, whichever size you use – and don’t forget to pick up some appropriate hose clamps.

Now take some of your surgical tubing and create the in and out lines with fittings at either end – a beer keg out fitting at one end, and a beer out fitting at the other end. By using a beer out fitting at both ends, you will be able to go from keg, through the filter, and into the final keg without risk of contamination. You will need to hook up the garden hose to back-flush the filter after use. Then, you can sanitize it and store it in the fridge. Depending on the model of filter you use, you may be able to filter up to 100 gallons of beer with a single filter.