Hi Mike,
The ideal soil moisture level depends on your plant type. For example, we recommend set moisture low as 50% and high as 80%, which means when the moisture level is higher than 80%, the next watering will be skipped.
For grass, we recommend set moisture low as 70% and high as 90%. In average, 80% for your zone is fine.
Thanks,
Netro Support
Regarding your dropped moisture level, we have received your email. We will have our technician look into this issue and get back to you soon.