Foam Stopper

Has anyone used the foam stopper for fermentation instead of the traditional bubble lock? What is your experience. I have just used one on a starter and it seemed to work ok, but what is the long term (1 week or so) likelyhood of contamination getting in on a 5 gal batch of beer?

OK brain fart. When you say foam stopper, are you describing some kind of bung that goes in the neck of the carboy, or a liquid you put in to the wort to keep the krausen from building up?

If it's the former, then I don't see why it wouldn't work as long as there's positive pressure coming out of the carboy. If it's the latter, well then I don't know what you're talking about.

These breathable foam stoppers will withstand boiling or autoclaving temperatures, making them ideal for use in preparing a yeast starter. The honeycomb structure of the foam stoppers will act is a filter for any airborne bacteria or wild yeast that might enter the flask. That's important because a lot of air is sucked into the flask while it is cooling. You can also leave the stoppers on the flask instead of a fermentation lock. Some people use foam stoppers to replace fermentation locks in their carboys, too.
The small foam stoppers are 35-45mm wide and fit our 1000 ml Pyrex flasks, or a glass carboy. The large stoppers are 46-50mm wide, and fit 2000 ml Pyrex flasks.

At least that's what the add says.

Ressurecting the Thread....


I have just started using foam stoppers on two carboys. So far, the biggest change is that the entire house smells like beer yeast.

I've been using the foam stoppers on my 2 liter starter flasks for at least a couple of years with zero problems. The open cell foam is essentially a maze of very tiny tunnels. Bacteria have no means of self propulsion. ie, they can't crawl, so any that enter the labyrinth soon get trapped and none make it through to the wort. Gases, however, pass freely in both directions. ie CO2 out and O2 in. The stoppers are washable and can be reused. I give them a soak in hot Oxyclean followed by a cold water rinse then use Starsan as the final sanitizing step. The stoppers offer some added protection over the foil method, but I've never had a problem doing it that way either. I have not found it necessary to autoclave or boil the stoppers.

I always use foam stoppers on starter flasks. I tried one on a 6.5 ga. carboy, but a healthy fermentation blew it right out. It will work but I would put a piece of tape over it to keep it in place or you may come home and find your fermenting beer has been exposed to air all day. I never did try it again, but would be afraid of pressure build up in a carboy if it did'nt release CO2 fast enough at the high point of fermentation.

Where can a person purchase a foam stopper (the tangible kind) for use with carboys and starter flasks?

Northern Brewer sells them I know

Re-resurrecting this thread, I found this post because I was Googling about using these for starters. As posted above, it says "...a lot of air is sucked into the flask while it is cooling" which got me wondering when you actually put it on. Do you boil with it on, then cool, then pitch the yeast? Put it on before cooling?

I just have it in a bucket of starsan while I am brewing

rmullins said:

I just have it in a bucket of starsan while I am brewing

Click to expand...

When making starters? I'm wondering if the suggestion is to put it on the starter flask before cooling.

use a blowoff tube and a jug of starsan. no messy accidents that way