BattleOfYakima
TFP Guide
You are correctly adding chlorine to SLAM level. It works hard to kill bacteria, algae, viruses, and organic matter. This process uses up FC (chlorine either bound to CYA or available to sanitize) and this used up FC becomes CC (chlorine not able to sanitize and bound as stinky chloramines). Luckily, at SLAM FC levels these CC are broken down by FC and burned off by the sun during the day. So your tests showing CC kind of confirm you are killing stuff off, and it's waiting for the sun to burn it off.