How long will mixed star-san stay effective?

[damdaman]

I usually mix up a large batch and then keep the extra in jugs to use as needed, sometimes for months. Will this stuff remain effective like that, or will it lose potency over time?

 

[Qhrumphf]

It depends on a number of factors. From what I understand, Star-San mixed distilled water and kept in a sealed container will keep for a very long time. Mixed with tap water and left in an open bucket not so much. Cloudiness is often an indicator, but I believe the final indicator is pH. One it rises above a certain level (which escapes me, but I think it's in the 2s or 3s), you can drop the pH down with a little more Star-San to "sweeten the pot".

 

[duboman]

A mix with distilled water will last about 3-4 months, tap water 1-2. If the pH rises above 3 then it gets tossed

 

[PastorofMuppets]

its worth it to prep star san with distilled water.
makes it last a decent while.

while not scientific it is reasonably true that cloudy star san is not going to keep long.
star san with distilled stays clear for a while.

when i make it with my tap water it clouds instantly

 

[damdaman]

Interesting, thanks for the info... I will have to see if the stuff I've had for a few months is cloudy or not. And get some pH strips.

 

[Qhrumphf]

Interesting, thanks for the info... I will have to see if the stuff I've had for a few months is cloudy or not. And get some pH strips.

Cloudy is an indicator. You ultimately need to know the pH. I don't used distilled for mine, just tap water, and it's cloudy right away, but the pH stays good for a long time.

 

[Black Island Brewer]

Mixed with tap water and left in an open bucket not so much. Cloudiness is often an indicator.

I don't used distilled for mine, just tap water, and it's cloudy right away, but the pH stays good for a long time.

pH will be the best test. Everyone's tsp water is different, so cloudy vs noncloudy may not be the best test. My tap water had less minerals than some people's RO water, but I mix 5 gallons and dump it every other month because I don't have a pH meter...yet.