I have heard about using irish moss in ales as a clarifyer... how do you use it? How much? When? And does it affect the taste of a beer? I am planning on using it with an Irish Red Ale Extract kit.... any suggestions you would have would be great.

3 Answers 3


Irish moss is available at any homebrew supply outlet, often in small bottles with the instructions right on the label. Use 1 tsp. per 5 gallons of beer at the last 15-20 minutes of the boil. It will not affect the flavor of the beer with such a low dosage, assuming you're not harvesting it yourself. Its purpose is to latch onto proteins in the beer and pull them out of suspension, thus removing the "haze". It is best when used in combination with a crash cool, but accomplishes plenty on its own.


Al Korzonas did some tests years back about using Irish moss. His findings were that you should use 1/4 tsp. in extract beers and 1 tsp. in all grain beers. The reason for using less in extract beers is due to the processing of the extract. For best results, rehydrate the Irish moss in a little water for an hour or so before using it.


Check out Whirfloc, an alternative to Irish moss. 1/2 - 1 tablet 15 min left in the boil should help your cold break flocculate.

  • The manufacturer of Whirlfloc recommends adding it 5 min. from the end of the boil.
    – Denny Conn
    Commented Dec 22, 2011 at 17:51
  • Also, I believe Whirlfloc is just processed Irish Moss. Think of it as pellet hops are to whole hops, Whirlfloc is to Irish Moss. Commented Dec 22, 2011 at 21:14

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