OK, First time using the TF-100 kit. I fill the CYA mixing bottle under the label, I add R-0013 to above the label. Shake, wait 30 sec, shake, I then hold C A tube at waist and slowly fill. So when the black dot disappears, that is my reading? Does the water become cloudy in the tube? I filled the tube and still could see the black dot. What am I doing wrong? Or is it that my CYA level is very low and need to add some?