I'm not trying question any of the experts on this site; I've found this site to be incredibly helpful when opening my pool this year. However, most of the guidelines I've read suggest keeping the free chlorine level at 1-3 ppm. The CYA chart on TFP has much higher FC level recommendations. For example, my CYA level is 50 and the chart shows 4-8 ppm should be the goal maintenance FC. Is there something I'm missing? Why the higher level here?