I'm another one who is still using stuff from years ago and it seems fine. I actually use my OTO kit for a lot of my day-to-day testing so some of mine last a long time before I need to replenish. Uncle Al keeps me supplied with cya reagent, etc. when I do need refills since he buys things in bulk. He doesn't have a bunch of boys who eat non-stop at his house like I do. No room in my frig for pool testing chemicals!