Every once and a while I like to do an OCLT. I guess it's the OCD coming out in me, so the wife just lets me be. Anyway I tested and got a base then took the pool up to my high target tonight with fresh Walmart bleach. Tested an hour or so later and have overshot my target by 3.5. Now after several years of testing I feel very confident in my testing skills. Nothing has changed. The volume is the same, my testing and dosing trends show no change. I start playing around on the poolcalculator changing % from 8.25. I get to 12% and it's the same amount I dosed the pool. Scratching my head I go out and look at the bottles. Shows 8.25% but the date code shows 196 or July 15th out of the Texas plant. Talk about short shelf life. I am looking at it as a fluke but we'll see what the other 4 bottles do.