Star San Mixture Shelf Life

Ok say I mix up a gallon of sanitizer using star san. How long will it last in that gallon? Say I put it in a cleaned out milk jug or something.

I've had a keg full for months and it is still going strong. I've got a squirt bottle that is running low but was filled maybe six months ago. Many people have stuff that has gone way longer than that. ph testing is the best way to be sure (I don't) or just look for it to cloud up.

If you mix it up with RO water, it will last indefinitely. I have a 5 gallon keg of it I mixed up a couple of years ago, and it's still working great (low pH & clear, which means it's fine). You know your Starsan mix needs more Starsan when it becomes cloudy.

I mix mine up with distilled water and it keeps forever ( or at least until I use it all ).

I have mixe4d StarSan into a 5 gallon carboy of RO/Distilled water and it has maintained it's initial pH for nearly 2 years. Even through a winter freeze (yes ice crystal formed in the solution) and summer heat (~90*F in the garage).

I always checked the pH everytime before use (with a calibrated meter) and it was always spot on at 3.0.

+10 on the RO or distilled water. Hard water will spoil it fast. I used well water and it only went about a week before cloudy, and it probably wasn't fit to use for several days before it became obvious.

With my tap water, a mix of starsan seems to cloud right away. Does that mean it is no good from the start? Do I need to use a higher concentration?

I'm not sure about that. the way to be sure is to test the pH. It should be no higher than 3 if I remember correctly. Just sticking to RO water is easier than worrying about it IMHO.

lschiavo said:

With my tap water, a mix of starsan seems to cloud right away. Does that mean it is no good from the start? Do I need to use a higher concentration?

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I contacted the company directly about that. They said that it is good for a little while but won't be effective for prolonged periods. In other words, you have to use it right away and toss it. The surfactant comes out of solution due to the hard water. Here is the exact message I got from them:

"If the solution turns cloudy it is starting to go bad. The surfactant is coming out of solution. If you use DI water from the store, it won’t happen. If you use the cloudy solution, you should be fine, but don’t let it sit for a too long. Over time it will continue to get worse and not be effective."

So I too have switched to distilled water and I test the PH each time to make sure. That stuff is too expensive not to reuse!

Yep, depending on water the shelf life is somewhere between 1 month and the heat death of the universe.

knightbeer39 said:

I contacted the company directly about that. They said that it is good for a little while but won't be effective for prolonged periods. In other words, you have to use it right away and toss it. The surfactant comes out of solution due to the hard water. Here is the exact message I got from them:

"If the solution turns cloudy it is starting to go bad. The surfactant is coming out of solution. If you use DI water from the store, it won’t happen. If you use the cloudy solution, you should be fine, but don’t let it sit for a too long. Over time it will continue to get worse and not be effective."

So I too have switched to distilled water and I test the PH each time to make sure. That stuff is too expensive to to reuse!

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Thanks for the info. I had always wondered but never had an infection.

We usually mix a few gallons per brewday and dump it afterwards. I have started mixing small batches in a spray bottle with distilled water for use between brewdays. That does stay nice and clear.

A few times in the past I have left things soaking in starsan overnight or for a few days. They end up really slimy feeling. That must be the surfactant I guess?

lschiavo said:

Thanks for the info. I had always wondered but never had an infection.

We usually mix a few gallons per brewday and dump it afterwards. I have started mixing small batches in a spray bottle with distilled water for use between brewdays. That does stay nice and clear.

A few times in the past I have left things soaking in starsan overnight or for a few days. They end up really slimy feeling. That must be the surfactant I guess?

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I think so, and I HATED that slimyness! It made everything look filthy. With the cleared starsan in distilled, everything looks clean and no slimy!

Glad I found this Cheers