I had an ammonia kit that was supposed to be good till 2008. Bought more than a year ago. Once I used up my other kit, I started testing my tanks with this one. Ammonia was up. Numerous water changes, no change in readings. So one day did a 50% change in one of the tanks, when tested, ammonia was higher. I thought that is insane! Went and bought a new test kit, things were fine!
Caper