I'm confused about something. You said this was a new pool and you thought you needed to stabilize, but, you report a cya reading of 40. CYA is stabilizer, and 40 is a very good reading. You also say you are losing your chlorine reading overnight. How high are you taking your chlorine whenever you are adding bleach? (which I assume is what you are using for your source of chlorine)

By the way, welcome to the forum!