Clear, but no chlorine???

[BigDave]

Pick up a cheap OTO / pH test kit. The OTO (yellow drops) it is reliable well outside normal range and will tell you if chlorine is high or low.
Do you have a K-2006?
Dilute a pool water sample 1:1 with tap water and measure CYA of diluted sample(then multiply by 2). If it's still over 100 (200) then dilute a pool water sample 1:2 with tap water and measure CYA of diluted sample(then multiply by 3).