CYA Apparently 0, according to TFP test kit
Well, I guess we changed out more water during the hurricane rains than I thought. Recently, I have been adding more chlorine daily (2-2.5 ppm) to remain at my desired FC level of 6.5. That level was selected because my CYA level had been 60. With Hermine, we took out about 6" of water (which was refilled with rain) and with Matthew we took out about 8" of water (mostly re-filled by rain). I haven't measured CYA for probably 4-5 months since I use liquid chlorine.
Is there really some CYA remaining even though I am unable to make the black dot disappear? Should I attempt to add maybe 10 ppm and then re-check?
Note: I switched over to the TFP method about January 2016 and, after one SLAM, the pool has been perfect all summer. No issues with algae and the water has been sparkling. I used to get a major bloom every 3 months. No more!