I've had my pool for 2 years and by following everything I read here, my water has been crystal clear the whole time. This is my first time being stumped with the chemistry (and frankly, I might be making a big deal out of nothing). I use the TF-100 test kit and my CC levels have always been 0. A few days ago, I started measuring small levels of CC, usually just 0.5. I'm going on vacation in a week and didn't want to leave it until the last minute so I went straight to shock treatment. The water looks very clear and I don't see any algae blooms, but the CC level won't drop to 0. Last night, I passed the overnight test and technically the 0.5CC meets the requirement to stop shocking, but I'm still not comfortable with my vacation coming up. Am I making too big of a deal out of the low level CC or should I stick with the shocking and knock it all the way to 0?