I've recently switched to Starsan from B-brite, and have had, shall we say, very tenacious krausens. I know that the Starsan foam isn't harmful to the beer, but it's foaming up in the carboy to the point where it pushes material up into the airlock. I've had to switch out airlocks a few times now to prevent a kaboom.

It doesn't look like I'm getting more active fermentation, just that the bubbles in the krausen don't pop. It builds and builds with large bubbles until it gooshes out the top.

I've been using blowoff tubes instead of airlocks because of this, but I wanted to know if this is a known result from Starsan. Or am I mixing it too strong (I'm using the little measuring compartment feature on the bottle), or something else?


3 Answers 3


When you rinse the carboy, after using the star Stan you get a good rinse? Another possibility is the amount the fermentables that you were using. Another possibility could be your filling your carboy too much.

  • 6
    You should not rinse starsan!
    – Boubou
    Dec 18, 2019 at 2:14
  • I actually haven't been rinsing the carboy at all, just letting it sit upside down over a bucket to drain for a while. I was under the impression that rinsing wasn't necessary. I'll do that next time. Dec 18, 2019 at 13:15
  • 2
    Don't do it! You'll simply erase the effect of starsan by adding the bacteria's present in water. Foam is 100% correct
    – Boubou
    Dec 18, 2019 at 15:57

It's prolly normal and I doupt this foam comes from starsan. I get bigger reaction when my fermentation temperature is high and/or OG is high and/or yeast produce big krausen


It could be that the Star San cleans better, and that chemicals that inhibit foam (like fatty acids etc), get removed better. I personally use Star San sometimes to clean the kitchen range because of that.

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