Homebrewing Stack Exchange is a question and answer site for dedicated home brewers and serious enthusiasts. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Following inspiration from this question, I've set myself up with equipment to brew one gallon batches. The idea is to brew small batches to get a solid recipe down, then scale up to a larger batch.

Now, a 5 gallon recipe calls for 1 tsp of Irish moss (according to package directions). If I scale linearly to my one gallon batch, that's 0.20 tsp of Irish moss. I don't think I can be that precise with my measurements. If I err and use too much (0.25 tsp, for example, 25% more than what is called for!) what will be the side effects? Will my beer be "too mossy"?

share|improve this question
up vote 7 down vote accepted

I wouldn't even bother with Irish moss for a small batch size. If you are using a one gallon fermentor you should be able to find space for it in the fridge when its done. Cold crashing for a week or so would be more effective than irish moss anyway.

share|improve this answer
Excellent point and entirely correct. – TinCoyote Oct 4 '10 at 16:29
+1, I didn't realise cold crashing was more effective. Good to know. – Mark McDonald May 1 '11 at 7:15

No. The purpose of Irish Moss is to remove particulate matter from your beer. I wouldn't bother trying to use a precise amount. Use half of what you would normally use and call it good.

All Irish Moss does is gelatinize and the gelatin captures small particles to help clear the beer during the cooling phase. It doesn't and shouldn't taste or smell like anything. Whirlfloc does the same thing.

share|improve this answer
It does have a seaweed smell to it in the jar. I just wanted to make sure that I wasn't going to get any of the seaweed flavor in my beer. – Bill Oct 2 '10 at 22:31
Nope, it will be fine. The Irish Moss will melt in the pot and become gelatin. – TinCoyote Oct 3 '10 at 1:14

You are totally fine. Like TinCoyote said, the moss is ionically charged particulate that attracts oppositely charged particulates (protein in this case) and makes them heavier so that they fall from suspension together. It will settle and when you rack it off the trub you will be in great shape.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.