Needed pool supplies so had my water tested at pool store. Big discrepancy in chlorine levels. Store says fc is .68 & TC is 3.58. My test using Taylor k-2006 is fc is 9.5 ( shocked a few days ago) and cc is 0. Pool store says put 5# of shock. Water is clean & sparkling with no odor. Which test do I trust. I am thinking mine. Thanks for your help.