I love this site and completely trust the info I get from it. I'm just confused as to why the info i get from the pool store is so different? I shocked my pool last weekend and got my FC to 19 which is where the chart said it needed to be with my CYA. My total alkalinity was at 190, ph at 7.2. When i called the store and told them i shocked it and my FC was at 19 he acted like i was crazy. he said the highest they even test to is 10?? he also told me that my fc should be ok to keep it about 1 but the chart shows 3-4. Any ideas as to why the big difference?? Right now my FC is about 1 and cc is .5. Should i add some bleach to get my fc up? any suggestions on what number to set my chlorinator to?