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Just getting started on home brewing and I used boiled water in my airlock. I've seen that some places recommend using sanitizer as the airlock "fill". Is it ok to use straight up StarSan in there or should I dilute with water?

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In addition to answers below, vodka works fine too. – Fishtoaster Jan 17 '11 at 22:55
Fishtoaster: I only have a bottle of grey goose! No way! ;) will have to get some of the cheap stuff. – typeoneerror Jan 17 '11 at 22:57
Heh, yeah- I usually use whatever's cheap an on hand. Even that is usually only when I forget to save a bit of the diluted sanitizer from earlier in the brewday. – Fishtoaster Jan 18 '11 at 17:32
up vote 10 down vote accepted

You should absolutely dilute with water.

If you use a higher concentration of star-san than what is listed on the bottle, it will no longer be at a "no-rinse" safety level, and may harm you or your yeast if it spills into your fermentor.

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What you want in your airlock is something that will:

  1. Allow airflow only in the direction of lower pressure. This qualifies pretty much any liquid.
  2. Not have funk grow in it. This means something you could use to sanitize things, or anything with high alcohol content (eg, I use vodka sometimes).
  3. Not hurt your beer if it ends up getting sucked back down into the fermenter. This means no bleach or other rinse-required sanitizers, and no undiluted no-rinse sanitizers (since they cease to be no-rinse in high-concentrations).

You can starsan, but at in the same level of dilution recommended on the bottle. I usually just save a cup from when I sanitize my equipment on brewday and use a bit of that.

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Dilute it to the concentration recommended on the bottle. No reason to waste the stuff.

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Personally,I use cheap vodka. $10 for 1.75L.

Star san, even diluted, will eventually damage your plastic airlocks.
Cheap? Yes. Free? No.

I've had one contamination out of quite a few batchs and don't think that was the airlck's fault. Bad mash -> low fermentables -> poor start -> brett pellicle.

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