I used 3" tablets a few months ago but it took 1month to see the rise in cya from 40 to50. To my surprise 1 month later(sept 12,2015) it measured 60. I used the TF100 kit. 2 questions-1. Obviously I can up my FC level, but If I leave it at the present level FC=4 what are the consequences. 2. Why did kit take so long from the time the tablets dissolved to when it registered. I have tested cya about 1-3 days after they dissolved and found no readings.