Welcome to Canreef!
Sounds like your off to a very good start and have obviously done your homework (real parameters rather than "the water is good")
You may have some good established rock and sand, I started my tank with similar well cured rock and never had any appreciable readings. I did add a piece of cocktail shrimp into my tank to let it rot and see If I could get a spike but I guess the rock was established enough as even then nothing showed up.