Help Co2 Chart Confusion

[kjb66]

If my ph out of tap is 7.0 and kh is 10 this shows up as 32 on the chart,if i get my ph down to 6.6 it shows up on chart as 81,but my drop checker is still green this is why im confused.
any help would be great
thanks

 

[kjb66]

i have left some water for a while before testing ph from tap and its now reading 7.2,should the water be left awhile?