Why Do I Have Bubbles in My Beer Line? Diagnosing and Fixing Kegerator Foam Problems

Thanks to u/Procrastinator548 on Reddit for this photo

Got Bubbles?

Bubbles in your beer line can point to a several potential problems. These problems can lead to small bubbles… foam or larger CO2 bubbles breaking out of solution. These issues can occur at different points in your kegerator. The point at which they occur and specific behaviors can help us to track down the problem.

An Unbalanced System

First, start with a balanced system. You need the right combination of temperature, pressure and resistance to serve a proper pint of beer.

This will be a recurring theme throughout this article. Balancing your system is an important baseline. Most, but not all, of the troubleshooting steps outlined here revolve around diagnosing different versions of an unbalanced system.

See: Step by Step: Balancing Your Kegerator Draft System

Another Tool: Flow Control

As detailed in my step by step on balancing your kegerator temperature, pressure and resistance are the key factors when it comes to dialing in kegerator pours. Before I move on to diagnosing specific issues, I wanted to also mention flow control devices as an option for helping to easily balance your system without the use of long lengths of tubing.

Flow control devices feature a built in flow compensator that allows you to adjust the resistance your faucet/line/device is exerting.  That means less tubing and potentially less foaming and wasted beer. The compensation feature also makes it easier to serve higher carbonation beers as you can set the faucet to provide resistance to offset the increased pressure needed to store and serve these beers at higher pressures.  Instead of replacing your beer line with ever increasing lengths of tubing, you simply turn a knob to increase resistance.

See the end of this article for flow control options

First Foamy Pint

Temperature is fundamental when it comes to serving beer. It will appear throughout this resource.

The first foamy pint issue is a common problem and easy to diagnose. With this issue you’ll get a… first foamy pint and then subsequent beers poured soon after will be great.

This is caused by warm beer lines or other warm equipment in the path of your beer. The beer that’s sitting in your beer lines is warming up.  Warmer beer does not hold CO2 as readily.  Your warm-ish beer hits the faucet and whammo… you get foam for the first couple pours.  The problem clears up because your lines, shanks and faucets cool down after you’ve run enough beer through the lines.  I’ve seen people discard half a pitcher of foamy beer before things clear up.  Lost beer isn’t good.

The solution revolves around getting and keeping your lines chilled as much as possible

  • Use a recirculating fan to stamp out warm spots.  I have a freezer based kegerator/keezer and this has resolved the first foamy pint issue for my kegerator.  See: Kegerator Beer Line Temperatures & Reducing Foam with a Recirculating Fan
  • If your kegerator has a draft tower, consider getting a tower cooler.  These are fan setups that are designed to blow cold are into your tower.  Cooling the tubing and tower down. Search “Beer Tower Cooler” on Amazon to look for some options.
  • Neoprene Wraps are available that further insulate your tower.  These should help reduce foam and help save on energy.  Search “kegerator tower insulation” on Amazon to look for some options
  • Use longer shanks.  A longer shank means… a colder faucet.  A colder faucet means less foam.  Credit for this tip goes to Tom Schmidlin.
  • For longer runs that go outside your kegerator, considering a recirculating coolant line.  This line would run alongside your beer lines circulating cold liquid.  Commercial establishments use recirculating glycol lines for this purpose.  Those are generally very expensive.  You could build a similar budget setup by recirculating water using a utility pump.  You’ll also want to insulate those lines.  Search “propylene glycol” on Amazon
  • Brass Draft Beer Shank Cold Block – These thread on to your standard shank to let you run glycol or water lines through them.  Cold shanks and faucets mean less foam. Search eBay for “brass cold block”
  • Nukatap Faucets – One of the specific design goals of this faucet.  Reduce thermal mass to reduce foaming.

Over-Carbonated Beer

Thanks to u/Procrastinator548 on Reddit for this photo

Your beer has been over carbonated because of an unbalanced system or over zealous force carbonation.

A sign that this could be the problem is that multiple pints served one after another pour foamy.

See: Fix Over-Carbonated Beers with a Spunding Valve

Beer Line Too Warm

Heat rises. This causes the top of your kegerator to be warmer than the center and bottom of your kegerator. In all likelihood your faucets, shanks and some tubing are in the warmer part of your kegerator. This causes CO2 to come out of solution and causes foam.

A sure sign that this is the problem is that the first pint pours foamy and subsequent pints poured soon after pour correctly. The problem comes back again after a longer period of time as things warm up again.

A solution to this is to add a recirculating fan to even out temps.

See: Kegerator Beer Line Temperatures & Reducing Foam with a Recirculating Fan

Pressure is Too Low

Photo via the BA’s Great Resource, Demystifying Dispense Gas

Another problem related to improper balancing. If your serving pressure is too low for the resistance of your system you can get foaming or bubbles.

A sign that this could be the problem is foam starts occurring at some point after leaving your keg. There is a length of tubing that looks good and then later you can visibly see foam in the tubing.  This can be while you’re serving beer or co2 can breakout causing visible pockets in the beer line.

See: Step by Step: Balancing Your Kegerator Draft System

Pressure is Too High

If pressure is set too high you’ll get foaming at the faucet. It’s also quite likely that your beer will also be over-carbonated.

A sign that this could be the problem is that beer looks good in tubing and you get excessive foam at the faucet. This would typically be accompanied by the beer serving too quickly.

See:

Beer Line Too Short

If pressure is set too high you’ll get foaming at the faucet. It’s also quite likely that your beer will also be over-carbonated.

A sign that this could be the problem is that beer looks good in tubing and you get excessive foam at the faucet. This would typically be accompanied by the beer serving too quickly.

See:

Diagnosing Between: Pressure Too High vs Beer Line Too Short

These issues can present themselves the same way. Fast pours and excessive foam that starts at the faucet. One troubleshooting step you can take is decreasing pressure, venting keg head space and serving a pint. If the pint is too carbonated and excessively foamy, it’s probably a pressure issue. If the beer serves okay, it’s probably a beer line length issue.

Slow Flow, Cavitating Bubble When Serving

Thanks to u/lolwatokay on r/homebrewing for this photo!

This problem presents itself at the faucet with cavitation at the tap. An air bubble is trapped within the beer while serving.  This is generally a flow rate issue, caused by incorrect pressure or resistance, a blockage or potentially a dirty faucet that’s gumming up the works. If you’re certain your system is correctly balanced, clean the line and faucet and take apart everything on the liquid side to ensure it’s properly assembled.

Large CO2 Bubbles in Beer Line

Keg Dip Tube O-Rings - Food Safe Silicone

Continual, larger CO2 bubbles in your beer line while serving.

A bad gas dip tube o-ring or a gas post o-ring is allowing head space CO2, in the case of the dip tube o-ring, or atmospheric air, in the case of the post o-ring, into the line at the time of vending.

Replace both post and dip tube o-rings and re-assemble everything on the gas side to make sure everything looks good and is installed and seated properly.

See:

Obstruction

An obstruction can cause turbulence which results in foaming issues. The obstruction could be at an point in your setup. Dip tube, post/poppet, beer line, shank or faucet. The most likely culprit for this would be hop or other trub material.

What Else?

Diagnosing these sorts of issues can be frustrating. Have you run into a scenario that isn’t outlined here? Got a comment or tip related to one of these conditions?  Got a correction? Do you have a photo that nicely illustrates one of these issues that you can share to help your fellow homebrewer?

Let me know!

Flow Control Faucets and Devices

Flow control devices feature a built in flow compensator that allows you to adjust the resistance your faucet/line/device is exerting.  That means less tubing and potentially less foaming and wasted beer. The compensation feature also makes it easier to serve higher carbonation beers as you can set the faucet to provide resistance to offset the increased pressure needed to store and serve these beers at higher pressures.  Instead of replacing your beer line with ever increasing lengths of tubing, you simply turn a knob to increase resistance.

Intertap Stainless Steel Forward Sealing with Flow Control
Intertap forward sealing faucets have a unique modular, threaded spout design which can fit a variety of different attachments including a growler filler, stout spout and ball lock post.  Check out my Hands on Review of these great faucets.

Intertap+Flow Control have been largely discontinued. The great news, at least as of this posting, is that Nukatap+Flow Control are generally available…

NUKATAP Stainless Steel Forward Sealing with Flow Control
These are Kegland’s follow up to their great Intertap lineup.  They work with all Intertap accessories and sport a number of improvements.  Check out our Hands on Review of these great faucets.

Perlick 650SS

More Flow Control Faucets

Flow Control Devices

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