I ran a full test of water on Thursday evening 7/5. FC 4.5, CC 0, PH 7.5, CYA 50, TA 100, CH 130.
ON Friday evening, just checked FC 2.5, CC 0, PH 7.5 and I added 4 cups of Bleach that should have brought my FC up about 2.5 ppm to a total of 5 ppm. I checked this morning 7/7 and the FC checked at 3.5 ppm, CC 0. My question is, do I need to be concerned with a supposed 1.5 to 2 ppm drop over night. What will tell me if, and when, I should shock the pool?

btw, My Cya test on Wed. 7/4 showed only 30. ( a >20ppm drop in 2 days, >50 on Mon 7/2.) I added a bioguard silk stick as it is the only stabilizer I have. It did do its job and brought the CYA up to 50 on 7/5. I read where I only need to test CYA once a month. I guess this will be when my new pool is completely balanced for a while. Any advice?
Thanks!