To give more detail to Big Dave's advice (which is sound), I don't like CYA to be below 30, and generally don't like it to go over 50, because there your maintenance level of FC is 3 to 6 ppm. But, if you find at that level of CYA you are adding chlorine all the time, then by all means raise it to the 60 to 80 level and maintain FC at 5 to 10 ppm.