This is quite the eye opener, I’ve been using Starsan for years and never knew it only was good for an hour. I usually make a gallon mix at a time, So either it works or I’ve been lucky. I’ve always thought that So2 degraded faster so didn’t use it for sanitizing. I guess I’ll mix up starsan as needed till it’s gone, then switch to So2.
I found a old batch I mixed up 3 years ago. The ph was still good so used it. No issues yet. But certainly some interesting reading.