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Whirlfloc tablets


Forum Moderator
Grandmaster Brewer
Aug 25, 2008
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A friend tipped me off to this info and we found confirmation on other sites, so I'm sharing what we found "on the internet." 

Whirlfloc tablets were made to be a commercial-use product for large batches; the maker didn't know distributors were re-packaging for the homebrew market until recently.

Two 2.5 gram tabs (5 gm total) will treat one hectoliter, or 25 gallons, so one tab does 12.5 gallons, so a full tab is more than needed for five gallons.  If you're treating 5-6 gallons then half a tab is plenty.  And it's carrageenan with a wax binder to maintain the tablet form, so essentially same as irish moss. 

There is also information out there that the longer it boils the more it gets denatured and loses some binding power.  I'm going to try five minutes next time I brew. 
FWIW, the package I bought had those quantities on the label. I've always used a half tablet in a 5 gallon batch.

The part about the length of time of boiling it is interesting and news to me. I have been throwing it in around the 20 minute mark but will try a batch with a shorter boil time for the Whirlfloc. I've also read that anywhere from 15-30 minutes for it is fine but that may be IM that I'm thinking of.

Thanks for posting the info!
MaltLicker said:
Two 2.5 gram tabs...

The tabs I use only weigh 1.0 gram, they are packaged for Brewcraft. Directions say 1 tab per 5 gallon, 15 minutes before end of boil. I use 1/2 tab because I Mini-BIAB and my beer is clear.

Just my two cents.
I always get mine at MoreBeer and they also indicate 1 tablet is good for 10-15 gallons and recommend 1/2 for 5 gallons. 

I always use 1 tab in my 5.5 gallon batches because I never realized I should cut it in half.  I follow MoreBeer's recommendation at 5 minutes before flameout (which the post below says is the right time).

This post has useful information from the manufacturer.  http://www.homebrewtalk.com/f39/whirlfloc-37012/

Thanks for posting this MaltLicker.

Yea, we'll see.  I did one gram at five minutes Saturday.  Lots of leaf hops, but wort seemed pretty clear.  Went into a bucket instead of the usual carboy so I didn't get the visual comparison. 
I used Whirlfloc for the first time on Wednesday after 20 years of using Irish Moss.  Two tabs in a 10 gallon batch.  Just by looking at the wort in the hydrometer sample, I can say it definitely cleared out faster and had a certain brightness to it very quickly. 
I'm curious to know if you guys still added Irish Moss (in addition to the Whirlfloc).
Has anyone determined that a whole tablet in a five gallon batch works any better (or worse) than a half tab?