Starsan - how long does it keep

[MikeBusby]

If I mix up some Starsan (or equivalent) and put it in a spray bottle, how long will it remain potent?

 

[user 18729]

A very long time! If you’re unsure just check the PH is below 3 and it’ll still be effective

 

[cossie.j]

If you’re using either de ironised or distilled water? Probably a few weeks. If you’re using tap water and you have high alkalinity, a week at best is what I’ve found. One way to keep track is to buy a ph meter and as long as its PH3 or below, its good to use. I see many people mixing quite big quantities at a time and it lasting them months? Personally i buy 5 liter bottles of distilled water for spray bottles of starsan solution, and on brew day I’ll mix up a 10 liter batch with tap water and chuck it at the end of the day. It’s probably still good to use for next brew day? But I don’t take that risk as it’s only tiny amounts we use so I’m happy just binning it.

 

[SteveH]

I live in a hard water area and find that after a week or so left in a bucket you end up with a slimy residue in the bucket (and all over whatever is in there)

For a spray bottle I use pre-boiled water which doesn't seem to have the same issue so I presume it's the solids from the hard water precipitating

 

[fuggled]

Starsan, or chemsan, or whatever it’s sold as now, works by being an acid. Get yourself some litmus paper from eBay and then you can check before you use it. That’s what I do. Undiluted it lasts for years I think, but once it’s diluted just check the acidity.