Hop Filter Experiment

So as anyone who reads this knows I have been having some issues with my kegs becoming clogged which appears to be from hop debris getting stuck in the liquid out post of the keg.

Hop Filter 4

So, I have determined that my racking technique is poor and could use some attention. The obvious way is to be more careful and more discriminant in my racking. This I can work on. But, I was also interested in possibly adding some sort of course filtration system to my racking system to double insure that I will rack only clear beer. My initial idea was for an in-line filtration system. I imagined some sort of filter on the out-going hose between the carboy and the keg. I also thought about the same idea but instead located at the input location of the racking cane or at the output location of the hose from the racking cane.

While on lunch one day I daydreamed a sketch for the inline version of the hop filter. It seemed to make sense, my biggest questions were what to use as the filtration material and how long should it be. I decided on using a stainless-steel braid butchered from a water line. I have heard of people using these for straining out a grain bed in a mash tun with great success. Then I decided to make it about six inches long just to help avoid any weight issues since the contraption was made out of stainless steel, rubber, and brass.

The parts were easy enough to find, though I would have rathered everything was stainless steel, but the brass was NSF rated and it was really just a proto-type at this point. I bought all the parts and threw it together in about 30 minutes. Next I added 1.5oz of pellet hops to a glass carboy with 5 gallons of water. I had to let the hops “dissolve” so that they were no longer pellets and were more of a particulate. I was amazed how much hop debris was in the water, it was literally green. I can only imagine what it looked like when I brewed my Pliny the Elder clone and it had about 6oz of dry hops in it. I also realize that under normal circumstances the hops would have settled for a week plus, but I really wanted to test the filter under a worse case scenario type of atmosphere. So after all the hops had “dissolved” the experiments began.

Hop Filter 6 Hop Filter 1 Hop Filter 5   

First (Experiment #1) I tried the in-line filter. This is really the one I wanted to work because I like the way it worked and it was the most expensive and time consuming to work on (though it wasn’t really expensive nor time consuming). So I hooked the filter up basically right off of the racking cane. At first, because of the size of the tubing used on the filter (1 inch inner diameter), the chamber would not fill with beer, thus the suction for the racking would not occur. Not that I would want to do this with beer, but I “pumped” the Auto-siphon a few times and things got moving. I figured I was initially testing its filtration capabilities and the efficiency of the rest of the design could be questioned later. So the racking cane pulled much hops and the filter appeared to catch 90%+ of the hops, I was definitely impressed. But you could almost watch the filter clog. The hops were so dense and the filter material so tight it actually caked all of the holes closed on the filter. First it slowed, then it stopped, at about 2.5 gallons. Experiment #1 = Failure. I would say that it slightly worked, but not with this design. It makes me wonder if the filter was longer how much better (or worse, that’s a big chamber to fill) it would do, say at twelve inches or eighteen inches long.

Hop Filter 2Second (Experiment #2) I tried the filter at the end of the racking hose. The idea here was similar to the little lint filter you would put from your washing machine before the utility sink. My expectations though were that it would work the same, that is it would clog internally and eventually lead to the beer “squirting” out through whatever opening were available. So I set the experiment up the same and began racking. This time things began to run fine, but after a short while it was obvious that more hop debris was getting through than the inline. It wasn’t a lot, but it was enough that a small circle of hop debris formed in the middle, maybe the size of a quarter, but quite possibly still enough to clog a keg. Eventually the flow began to slow and then all but stopped, again at about 2.5 gallons. Experiment #2 = Failure. This again lead me to question how much of a difference the length of the filter would make.

Hop Filter 3Third (Experiment #3) I tried the filter at the beginning of the racking cane. The idea here was similar to a fish tank filter where it draws the water from the tank up through a course filter and then through a fine filter, though I would not be including a fine filter. Also, just because I could and it kind of made sense, I used an extra piece of stainless steel filter material that was about twice as long to see if that helped. So I set the experiment up the same and began racking. No problems getting the flow going again this time. Almost instantly it was obvious that with this technique the most about of hop debris got through. Again, not really a lot, but maybe twice the amount then Experiment #2. The flow did slow and it took about ten minutes or so to rack the entire 5 gallons of hop-water, but it did rack and filter the entire 5 gallons. Experiment #3 = Partial Success. It was a partial success for it did filter out hop material, but it did not filter out all of the hop material. It did make me wonder how much of a difference the longer piece of filtering material made.

By this point I had been playing with the Hop Filter Experiment for a couple hours and was kind of burning out on it. So for now, I think it is pretty open-ended and inconclusive. I do wonder about lengthening the inline filter which was the one that filtered the best. I also wonder about possibly adding a filter at both the beginning and end point of the racking cane and hose, a double filter? What it really all boils down to is I just need to unlearn bad habits and relearn how to rack properly, because to me it must be my problem since no one else uses these kinds of products or else they would be commercially available. I also think if I dry hopped with whole hops I would have fewer issues, and if used with one of these filters could possibly have even fewer. Until the next experiment occurs.

8 Responses to “Hop Filter Experiment”

  1. Freyguy Says:

    The hopstopper in the boil pot works great, but a bit costly. I’d buy one again in a heartbeat though. As for racking, I’ve never really had an issue with the kegs. I think I mentioned it before, but when I dryhop with pellets, I normally just throw em in the secondary, then use a super long fine mesh nylon bag from the homebrew store over the autosiphon. I can’t get every last drop of beer out of the carboy with it, but it does a great job filtering out the pellet hop particles. With whole hops, I don’t really do anything, just make sure the tip is on the autosiphon. Just my 2 pennies incase they help.

  2. Brian Says:

    Thanks Bri – I’ve heard the HopStopper gets clogged with pellet hops, did you have that problem? Buy one again, did the other one break?

    I’ll figure out a way to make it so dry-hopping while kegging is a non-issue.

  3. garrett Says:

    The answer is… whole hops! :-p

    Actually pellet can work too… There was an article recently in BYO where they show how to make a carboy infusor from some tea ball wire mesh… its this long skinny thing. Not sure how good it does at keeping the hop debris from getting out, but its gotta be better than it floating loose.

  4. Brian Says:

    Yeah, I saw that thing, but for me the whole point of dry-hopping is exposure. I want my hops to be exposed to as much beer as possible and that thing seems restrictive.

    Yeah, I know, whole hops . . .

  5. garrett Says:

    I happen to know someone who has an @$$load of them…

  6. Freyguy Says:

    Nah, my hopstopper is still working just fine. I’ve never had any clogs, but sometimes it’s a bit slow starting. It’s turning a bit of a brownish color even though it’s stainless, so I think I should boil it in some PBW or something. I just mean I’ll buy another one if I ever need it. I’m thinking of buying a big pot so I can do 10g batches. I hope I can make this one fit on both pots though.

    I just listened through the Brewing Network podcast on IIPA’s, and they discussed hops a good bit. They mentioned alot of ways that the pro-brewers dryhop. They try to get the hops in suspension as long as possible. They pump O2 up through the conicals to push the hops back up, or sometimes they pump the wort from the bottom to the top. They also said that a dryhop schedule is best, not just throwing them all in there. Seems like alot of work, but it’s worth a listen.

  7. Andrew Says:

    My early beers were too astringent, and that was from leaving the hops trub in the carboy during fermentation (I made no attempt at all to seperate them in those days). Now I use the nylon boiling bags during the boil. That probably cuts utilization down a bit (maybe 15% from my memory of Palmer’s book) but it’s worth it to eliminate the astringent problem.

    It would work too with dry hopping I expect. Same issue of a slight loss of utilization, but you completely eliminate having any hops bits in the beer afterwards. You can always add a bit more hops to compensate.

    BTW did you harvest any hops this year? I had a Hallertau plant in its second year that produced about 3-4 flowers. It’s probably pining for Rhineland. A first year Sterling plant produced 30-40 flowers which worked out to about 1/4 oz dried, and a first year Mt. Hood plant did about a dozen flowers. I guess the American varieties really are better suited for this climate.

  8. Brian Says:

    I actually never planted my hops, they are still in a pot from when they were transfered from my old house to my new house. I need to get them back in the ground. My third year I got like a pound yield – sheesh.

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