I have a bucket of 2.5 gallons of water and StarSan that I used a few days ago to sanitize my hydrometer and wine thief to take a gravity reading. I've left it out uncovered over the past few days with the intention of using it to sanitize these items for another gravity reading. But as I was about to do that, I thought is there a chance the StarSan could lose its effectiveness from being left out. I don't want to chance it to save a bit of StarSan so I dumped it and created a new solution, but thought I'd ask what you all thought.